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2017-11-28debugfs: fix debugfs_real_fops() build errorArnd Bergmann1-0/+2
Some drivers use debugfs_real_fops() even when CONFIG_DEBUG_FS is disabled, which now leads to a build error: In file included from include/linux/list.h:9:0, from include/linux/wait.h:7, from include/linux/wait_bit.h:8, from include/linux/fs.h:6, from drivers/net/wireless/broadcom/b43legacy/debugfs.c:26: drivers/net/wireless/broadcom/b43legacy/debugfs.c: In function 'b43legacy_debugfs_read': drivers/net/wireless/broadcom/b43legacy/debugfs.c:224:23: error: implicit declaration of function 'debugfs_real_fops'; did you mean 'debugfs_create_bool'? [-Werror=implicit-function-declaration] My first impulse was to add another 'static inline' dummy function returning NULL for it, which would work fine. However, most callers feed the pointer into container_of(), so it seems a little dangerous here. Since all the callers are inside of a read/write file operation that gets eliminated in this configuration, so having an 'extern' declaration seems better here. If it ever gets used in a dangerous way, that will now result in a link error. Fixes: 7c8d469877b1 ("debugfs: add support for more elaborate ->d_fsdata") Cc: Jakub Kicinski <jakub.kicinski@netronome.com> Cc: Simon Horman <simon.horman@netronome.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07debugfs: Remove redundant license textGreg Kroah-Hartman1-4/+0
Now that the SPDX tag is in all debugfs files, that identifies the license in a specific and legally-defined manner. So the extra GPL text wording can be removed as it is no longer needed at all. This is done on a quest to remove the 700+ different ways that files in the kernel describe the GPL license text. And there's unneeded stuff like the address (sometimes incorrect) for the FSF which is never needed. No copyright headers or other non-license-description text was removed. Cc: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07debugfs: add SPDX identifiers to all debugfs filesGreg Kroah-Hartman1-0/+1
It's good to have SPDX identifiers in all files to make it easier to audit the kernel tree for correct licenses. Update the debugfs files files with the correct SPDX license identifier based on the license text in the file itself. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This work is based on a script and data from Thomas Gleixner, Philippe Ombredanne, and Kate Stewart. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Kate Stewart <kstewart@linuxfoundation.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07debugfs: purge obsolete SRCU based removal protectionNicolai Stange1-19/+0
Purge the SRCU based file removal race protection in favour of the new, refcount based debugfs_file_get()/debugfs_file_put() API. Fixes: 49d200deaa68 ("debugfs: prevent access to removed files' private data") Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07debugfs: debugfs_real_fops(): drop __must_hold sparse annotationNicolai Stange1-2/+1
Currently, debugfs_real_fops() is annotated with a __must_hold(&debugfs_srcu) sparse annotation. With the conversion of the SRCU based protection of users against concurrent file removals to a per-file refcount based scheme, this becomes wrong. Drop this annotation. Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07debugfs: implement per-file removal protectionNicolai Stange1-0/+11
Since commit 49d200deaa68 ("debugfs: prevent access to removed files' private data"), accesses to a file's private data are protected from concurrent removal by covering all file_operations with a SRCU read section and sychronizing with those before returning from debugfs_remove() by means of synchronize_srcu(). As pointed out by Johannes Berg, there are debugfs files with forever blocking file_operations. Their corresponding SRCU read side sections would block any debugfs_remove() forever as well, even unrelated ones. This results in a livelock. Because a remover can't cancel any indefinite blocking within foreign files, this is a problem. Resolve this by introducing support for more granular protection on a per-file basis. This is implemented by introducing an 'active_users' refcount_t to the per-file struct debugfs_fsdata state. At file creation time, it is set to one and a debugfs_remove() will drop that initial reference. The new debugfs_file_get() and debugfs_file_put(), intended to be used in place of former debugfs_use_file_start() and debugfs_use_file_finish(), increment and decrement it respectively. Once the count drops to zero, debugfs_file_put() will signal a completion which is possibly being waited for from debugfs_remove(). Thus, as long as there is a debugfs_file_get() not yet matched by a corresponding debugfs_file_put() around, debugfs_remove() will block. Actual users of debugfs_use_file_start() and -finish() will get converted to the new debugfs_file_get() and debugfs_file_put() by followup patches. Fixes: 49d200deaa68 ("debugfs: prevent access to removed files' private data") Reported-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07debugfs: add support for more elaborate ->d_fsdataNicolai Stange1-17/+3
Currently, the user provided fops, "real_fops", are stored directly into ->d_fsdata. In order to be able to store more per-file state and thus prepare for more granular file removal protection, wrap the real_fops into a dynamically allocated container struct, debugfs_fsdata. A struct debugfs_fsdata gets allocated at file creation and freed from the newly intoduced ->d_release(). Finally, move the implementation of debugfs_real_fops() out of the public debugfs header such that struct debugfs_fsdata's declaration can be kept private. Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-07-17debugfs: Add dummy implementation of few helpersViresh Kumar1-0/+16
This adds (missing) dummy implementations of debugfs_create_file_unsafe() and debugfs_create_ulong(). Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-05-16fs: update location of filesystems documentationMauro Carvalho Chehab1-1/+1
The filesystem documentation was moved from DocBook to Documentation/filesystems/. Update it at the sources. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2017-04-08debugfs: set no_llseek in DEFINE_DEBUGFS_ATTRIBUTEGeliang Tang1-1/+1
In DEFINE_DEBUGFS_ATTRIBUTE() macro, since we use nonseekable_open() to open, we should use no_llseek() to seek, not generic_file_llseek(). Signed-off-by: Geliang Tang <geliangtang@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-02-24Merge branch 'for-linus' of ↵Linus Torvalds1-1/+2
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull namespace updates from Eric Biederman: "There is a lot here. A lot of these changes result in subtle user visible differences in kernel behavior. I don't expect anything will care but I will revert/fix things immediately if any regressions show up. From Seth Forshee there is a continuation of the work to make the vfs ready for unpriviled mounts. We had thought the previous changes prevented the creation of files outside of s_user_ns of a filesystem, but it turns we missed the O_CREAT path. Ooops. Pavel Tikhomirov and Oleg Nesterov worked together to fix a long standing bug in the implemenation of PR_SET_CHILD_SUBREAPER where only children that are forked after the prctl are considered and not children forked before the prctl. The only known user of this prctl systemd forks all children after the prctl. So no userspace regressions will occur. Holding earlier forked children to the same rules as later forked children creates a semantic that is sane enough to allow checkpoing of processes that use this feature. There is a long delayed change by Nikolay Borisov to limit inotify instances inside a user namespace. Michael Kerrisk extends the API for files used to maniuplate namespaces with two new trivial ioctls to allow discovery of the hierachy and properties of namespaces. Konstantin Khlebnikov with the help of Al Viro adds code that when a network namespace exits purges it's sysctl entries from the dcache. As in some circumstances this could use a lot of memory. Vivek Goyal fixed a bug with stacked filesystems where the permissions on the wrong inode were being checked. I continue previous work on ptracing across exec. Allowing a file to be setuid across exec while being ptraced if the tracer has enough credentials in the user namespace, and if the process has CAP_SETUID in it's own namespace. Proc files for setuid or otherwise undumpable executables are now owned by the root in the user namespace of their mm. Allowing debugging of setuid applications in containers to work better. A bug I introduced with permission checking and automount is now fixed. The big change is to mark the mounts that the kernel initiates as a result of an automount. This allows the permission checks in sget to be safely suppressed for this kind of mount. As the permission check happened when the original filesystem was mounted. Finally a special case in the mount namespace is removed preventing unbounded chains in the mount hash table, and making the semantics simpler which benefits CRIU. The vfs fix along with related work in ima and evm I believe makes us ready to finish developing and merge fully unprivileged mounts of the fuse filesystem. The cleanups of the mount namespace makes discussing how to fix the worst case complexity of umount. The stacked filesystem fixes pave the way for adding multiple mappings for the filesystem uids so that efficient and safer containers can be implemented" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: proc/sysctl: Don't grab i_lock under sysctl_lock. vfs: Use upper filesystem inode in bprm_fill_uid() proc/sysctl: prune stale dentries during unregistering mnt: Tuck mounts under others instead of creating shadow/side mounts. prctl: propagate has_child_subreaper flag to every descendant introduce the walk_process_tree() helper nsfs: Add an ioctl() to return owner UID of a userns fs: Better permission checking for submounts exit: fix the setns() && PR_SET_CHILD_SUBREAPER interaction vfs: open() with O_CREAT should not create inodes with unknown ids nsfs: Add an ioctl() to return the namespace type proc: Better ownership of files for non-dumpable tasks in user namespaces exec: Remove LSM_UNSAFE_PTRACE_CAP exec: Test the ptracer's saved cred to see if the tracee can gain caps exec: Don't reset euid and egid when the tracee has CAP_SETUID inotify: Convert to using per-namespace limits
2017-02-22Merge tag 'driver-core-4.11-rc1' of ↵Linus Torvalds1-2/+1
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core updates from Greg KH: "Here is the "small" driver core patches for 4.11-rc1. Not much here, some firmware documentation and self-test updates, a debugfs code formatting issue, and a new feature for call_usermodehelper to make it more robust on systems that want to lock it down in a more secure way. All of these have been linux-next for a while now with no reported issues" * tag 'driver-core-4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: kernfs: handle null pointers while printing node name and path Introduce STATIC_USERMODEHELPER to mediate call_usermodehelper() Make static usermode helper binaries constant kmod: make usermodehelper path a const string firmware: revamp firmware documentation selftests: firmware: send expected errors to /dev/null selftests: firmware: only modprobe if driver is missing platform: Print the resource range if device failed to claim kref: prefer atomic_inc_not_zero to atomic_add_unless debugfs: improve formatting of debugfs_real_fops()
2017-02-02debugfs: add debugfs_lookup()Omar Sandoval1-0/+8
We don't always have easy access to the dentry of a file or directory we created in debugfs. Add a helper which allows us to get a dentry we previously created. The motivation for this change is a problem with blktrace and the blk-mq debugfs entries introduced in 07e4fead45e6 ("blk-mq: create debugfs directory tree"). Namely, in some cases, the directory that blktrace needs to create may already exist, but in other cases, it may not. We _could_ rely on a bunch of implied knowledge to decide whether to create the directory or not, but it's much cleaner on our end to just look it up. Signed-off-by: Omar Sandoval <osandov@fb.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-01fs: Better permission checking for submountsEric W. Biederman1-1/+2
To support unprivileged users mounting filesystems two permission checks have to be performed: a test to see if the user allowed to create a mount in the mount namespace, and a test to see if the user is allowed to access the specified filesystem. The automount case is special in that mounting the original filesystem grants permission to mount the sub-filesystems, to any user who happens to stumble across the their mountpoint and satisfies the ordinary filesystem permission checks. Attempting to handle the automount case by using override_creds almost works. It preserves the idea that permission to mount the original filesystem is permission to mount the sub-filesystem. Unfortunately using override_creds messes up the filesystems ordinary permission checks. Solve this by being explicit that a mount is a submount by introducing vfs_submount, and using it where appropriate. vfs_submount uses a new mount internal mount flags MS_SUBMOUNT, to let sget and friends know that a mount is a submount so they can take appropriate action. sget and sget_userns are modified to not perform any permission checks on submounts. follow_automount is modified to stop using override_creds as that has proven problemantic. do_mount is modified to always remove the new MS_SUBMOUNT flag so that we know userspace will never by able to specify it. autofs4 is modified to stop using current_real_cred that was put in there to handle the previous version of submount permission checking. cifs is modified to pass the mountpoint all of the way down to vfs_submount. debugfs is modified to pass the mountpoint all of the way down to trace_automount by adding a new parameter. To make this change easier a new typedef debugfs_automount_t is introduced to capture the type of the debugfs automount function. Cc: stable@vger.kernel.org Fixes: 069d5ac9ae0d ("autofs: Fix automounts by using current_real_cred()->uid") Fixes: aeaa4a79ff6a ("fs: Call d_automount with the filesystems creds") Reviewed-by: Trond Myklebust <trond.myklebust@primarydata.com> Reviewed-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-01-11debugfs: improve formatting of debugfs_real_fops()Jakub Kicinski1-2/+1
Type of debugfs_real_fops() is longer than parameters and the name, so there is no way to break the declaration nicely. We have to go over 80 characters. Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-12-13Merge tag 'driver-core-4.10-rc1' of ↵Linus Torvalds1-17/+27
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core updates from Greg KH: "Here's the new driver core patches for 4.10-rc1. Big thing here is the nice addition of "functional dependencies" to the driver core. The idea has been talked about for a very long time, great job to Rafael for stepping up and implementing it. It's been tested for longer than the 4.9-rc1 date, we held off on merging it earlier in order to feel more comfortable about it. Other than that, it's just a handful of small other patches, some good cleanups to the mess that is the firmware class code, and we have a test driver for the deferred probe logic. All of these have been in linux-next for a while with no reported issues" * tag 'driver-core-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (30 commits) firmware: Correct handling of fw_state_wait() return value driver core: Silence device links sphinx warning firmware: remove warning at documentation generation time drivers: base: dma-mapping: Fix typo in dmam_alloc_non_coherent comments driver core: test_async: fix up typo found by 0-day firmware: move fw_state_is_done() into UHM section firmware: do not use fw_lock for fw_state protection firmware: drop bit ops in favor of simple state machine firmware: refactor loading status firmware: fix usermode helper fallback loading driver core: firmware_class: convert to use class_groups driver core: devcoredump: convert to use class_groups driver core: class: add class_groups support kernfs: Declare two local data structures static driver-core: fix platform_no_drv_owner.cocci warnings drivers/base/memory.c: Remove unused 'first_page' variable driver core: add CLASS_ATTR_WO() drivers: base: cacheinfo: support DT overrides for cache properties drivers: base: cacheinfo: add pr_fmt logging drivers: base: cacheinfo: fix boot error message when acpi is enabled ...
2016-11-04debugfs: constify argument to debugfs_real_fops()Jakub Kicinski1-1/+2
seq_file users can only access const version of file pointer, because the ->file member of struct seq_operations is marked as such. Make parameter to debugfs_real_fops() const. CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org> CC: Nicolai Stange <nicstange@gmail.com> CC: Christian Lamparter <chunkeey@gmail.com> CC: LKML <linux-kernel@vger.kernel.org> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-10-28debugfs: improve DEFINE_DEBUGFS_ATTRIBUTE for !CONFIG_DEBUG_FSArnd Bergmann1-17/+27
The slp_s0_residency_usec debugfs file currently uses DEFINE_DEBUGFS_ATTRIBUTE(), but that macro cannot really be used to define files outside of the debugfs code, as it has no reference to the get/set functions if CONFIG_DEBUG_FS is not defined: drivers/platform/x86/intel_pmc_core.c:80:12: error: ‘pmc_core_dev_state_get’ defined but not used [-Werror=unused-function] This fixes the macro to always contain the reference, and instead rely on the stubbed-out debugfs_create_file to not actually refer to its arguments so the compiler can still drop the reference. This works because the attribute definition is always 'static', and the dead-code removal silently drops all static symbols that are not used. Fixes: c64688081490 ("debugfs: add support for self-protecting attribute file fops") Fixes: df2294fb6428 ("intel_pmc_core: Convert to DEFINE_DEBUGFS_ATTRIBUTE") Signed-off-by: Arnd Bergmann <arnd@arndb.de> [nicstange@gmail.com: Add dummy implementations of debugfs_attr_read() and debugfs_attr_write() in order to protect against possibly broken dead code elimination and to improve readability. Correct CONFIG_DEBUGFS_FS -> CONFIG_DEBUG_FS typo in changelog.] Signed-off-by: Nicolai Stange <nicstange@gmail.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-09-21debugfs: introduce a public file_operations accessorChristian Lamparter1-0/+17
This patch introduces an accessor which can be used by the users of debugfs (drivers, fs, ...) to get the original file_operations struct. It also removes the REAL_FOPS_DEREF macro in file.c and converts the code to use the public version. Previously, REAL_FOPS_DEREF was only available within the file.c of debugfs. But having a public getter available for debugfs users is important as some drivers (carl9170 and b43) use the pointer of the original file_operations in conjunction with container_of() within their debugfs implementations. Reviewed-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Christian Lamparter <chunkeey@gmail.com> Cc: stable <stable@vger.kernel.org> # 4.7+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-04-13debugfs: add support for self-protecting attribute file fopsNicolai Stange1-0/+26
In order to protect them against file removal issues, debugfs_create_file() creates a lifetime managing proxy around each struct file_operations handed in. In cases where this struct file_operations is able to manage file lifetime by itself already, the proxy created by debugfs is a waste of resources. The most common class of struct file_operations given to debugfs are those defined by means of the DEFINE_SIMPLE_ATTRIBUTE() macro. Introduce a DEFINE_DEBUGFS_ATTRIBUTE() macro to allow any struct file_operations of this class to be easily made file lifetime aware and thus, to be operated unproxied. Specifically, introduce debugfs_attr_read() and debugfs_attr_write() which wrap simple_attr_read() and simple_attr_write() under the protection of a debugfs_use_file_start()/debugfs_use_file_finish() pair. Make DEFINE_DEBUGFS_ATTRIBUTE() set the defined struct file_operations' ->read() and ->write() members to these wrappers. Export debugfs_create_file_unsafe() in order to allow debugfs users to create their files in non-proxying operation mode. Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-04-13debugfs: prevent access to removed files' private dataNicolai Stange1-0/+20
Upon return of debugfs_remove()/debugfs_remove_recursive(), it might still be attempted to access associated private file data through previously opened struct file objects. If that data has been freed by the caller of debugfs_remove*() in the meanwhile, the reading/writing process would either encounter a fault or, if the memory address in question has been reassigned again, unrelated data structures could get overwritten. However, since debugfs files are seldomly removed, usually from module exit handlers only, the impact is very low. Currently, there are ~1000 call sites of debugfs_create_file() spread throughout the whole tree and touching all of those struct file_operations in order to make them file removal aware by means of checking the result of debugfs_use_file_start() from within their methods is unfeasible. Instead, wrap the struct file_operations by a lifetime managing proxy at file open: - In debugfs_create_file(), the original fops handed in has got stashed away in ->d_fsdata already. - In debugfs_create_file(), install a proxy file_operations factory, debugfs_full_proxy_file_operations, at ->i_fop. This proxy factory has got an ->open() method only. It carries out some lifetime checks and if successful, dynamically allocates and sets up a new struct file_operations proxy at ->f_op. Afterwards, it forwards to the ->open() of the original struct file_operations in ->d_fsdata, if any. The dynamically set up proxy at ->f_op has got a lifetime managing wrapper set for each of the methods defined in the original struct file_operations in ->d_fsdata. Its ->release()er frees the proxy again and forwards to the original ->release(), if any. In order not to mislead the VFS layer, it is strictly necessary to leave those fields blank in the proxy that have been NULL in the original struct file_operations also, i.e. aren't supported. This is why there is a need for dynamically allocated proxies. The choice made not to allocate a proxy instance for every dentry at file creation, but for every struct file object instantiated thereof is justified by the expected usage pattern of debugfs, namely that in general very few files get opened more than once at a time. The wrapper methods set in the struct file_operations implement lifetime managing by means of the SRCU protection facilities already in place for debugfs: They set up a SRCU read side critical section and check whether the dentry is still alive by means of debugfs_use_file_start(). If so, they forward the call to the original struct file_operation stored in ->d_fsdata, still under the protection of the SRCU read side critical section. This SRCU read side critical section prevents any pending debugfs_remove() and friends to return to their callers. Since a file's private data must only be freed after the return of debugfs_remove(), the ongoing proxied call is guarded against any file removal race. If, on the other hand, the initial call to debugfs_use_file_start() detects that the dentry is dead, the wrapper simply returns -EIO and does not forward the call. Note that the ->poll() wrapper is special in that its signature does not allow for the return of arbitrary -EXXX values and thus, POLLHUP is returned here. In order not to pollute debugfs with wrapper definitions that aren't ever needed, I chose not to define a wrapper for every struct file_operations method possible. Instead, a wrapper is defined only for the subset of methods which are actually set by any debugfs users. Currently, these are: ->llseek() ->read() ->write() ->unlocked_ioctl() ->poll() The ->release() wrapper is special in that it does not protect the original ->release() in any way from dead files in order not to leak resources. Thus, any ->release() handed to debugfs must implement file lifetime management manually, if needed. For only 33 out of a total of 434 releasers handed in to debugfs, it could not be verified immediately whether they access data structures that might have been freed upon a debugfs_remove() return in the meanwhile. Export debugfs_use_file_start() and debugfs_use_file_finish() in order to allow any ->release() to manually implement file lifetime management. For a set of common cases of struct file_operations implemented by the debugfs_core itself, future patches will incorporate file lifetime management directly within those in order to allow for their unproxied operation. Rename the original, non-proxying "debugfs_create_file()" to "debugfs_create_file_unsafe()" and keep it for future internal use by debugfs itself. Factor out code common to both into the new __debugfs_create_file(). Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-04-13debugfs: prevent access to possibly dead file_operations at file openNicolai Stange1-3/+0
Nothing prevents a dentry found by path lookup before a return of __debugfs_remove() to actually get opened after that return. Now, after the return of __debugfs_remove(), there are no guarantees whatsoever regarding the memory the corresponding inode's file_operations object had been kept in. Since __debugfs_remove() is seldomly invoked, usually from module exit handlers only, the race is hard to trigger and the impact is very low. A discussion of the problem outlined above as well as a suggested solution can be found in the (sub-)thread rooted at http://lkml.kernel.org/g/20130401203445.GA20862@ZenIV.linux.org.uk ("Yet another pipe related oops.") Basically, Greg KH suggests to introduce an intermediate fops and Al Viro points out that a pointer to the original ones may be stored in ->d_fsdata. Follow this line of reasoning: - Add SRCU as a reverse dependency of DEBUG_FS. - Introduce a srcu_struct object for the debugfs subsystem. - In debugfs_create_file(), store a pointer to the original file_operations object in ->d_fsdata. - Make debugfs_remove() and debugfs_remove_recursive() wait for a SRCU grace period after the dentry has been delete()'d and before they return to their callers. - Introduce an intermediate file_operations object named "debugfs_open_proxy_file_operations". It's ->open() functions checks, under the protection of a SRCU read lock, whether the dentry is still alive, i.e. has not been d_delete()'d and if so, tries to acquire a reference on the owning module. On success, it sets the file object's ->f_op to the original file_operations and forwards the ongoing open() call to the original ->open(). - For clarity, rename the former debugfs_file_operations to debugfs_noop_file_operations -- they are in no way canonical. The choice of SRCU over "normal" RCU is justified by the fact, that the former may also be used to protect ->i_private data from going away during the execution of a file's readers and writers which may (and do) sleep. Finally, introduce the fs/debugfs/internal.h header containing some declarations internal to the debugfs implementation. Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-08debugfs: Add stub function for debugfs_create_automount().Jiaxing Wang1-0/+8
Add stub for debugfs_create_automount() for when debugfs is not configured in. Signed-off-by: Jiaxing Wang <hello.wjx@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-10-18debugfs: Add debugfs_create_ulong()Viresh Kumar1-0/+2
Add debugfs_create_ulong() for the users of type 'unsigned long'. These will be 32 bits long on a 32 bit machine and 64 bits long on a 64 bit machine. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-10-04debugfs: Pass bool pointer to debugfs_create_bool()Viresh Kumar1-2/+2
Its a bit odd that debugfs_create_bool() takes 'u32 *' as an argument, when all it needs is a boolean pointer. It would be better to update this API to make it accept 'bool *' instead, as that will make it more consistent and often more convenient. Over that bool takes just a byte. That required updates to all user sites as well, in the same commit updating the API. regmap core was also using debugfs_{read|write}_file_bool(), directly and variable types were updated for that to be bool as well. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Mark Brown <broonie@kernel.org> Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-07-20debugfs: Export bool read/write functionsRichard Fitzgerald1-0/+20
The file read/write functions for bools have no special dependencies on debugfs internals and are sufficiently non-trivial to be worth exporting so clients can re-use the implementation. Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Mark Brown <broonie@kernel.org>
2015-05-11debugfs: switch to simple_follow_link()Al Viro1-1/+0
Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-02-17debugfs: Provide a file creation function that also takes an initial sizeDavid Howells1-0/+13
Provide a file creation function that also takes an initial size so that the caller doesn't have to set i_size, thus meaning that we don't have to call deal with ->d_inode in the callers. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-01-26new primitive: debugfs_create_automount()Al Viro1-0/+5
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-15Merge tag 'driver-core-3.19-rc1' of ↵Linus Torvalds1-1/+16
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core update from Greg KH: "Here's the set of driver core patches for 3.19-rc1. They are dominated by the removal of the .owner field in platform drivers. They touch a lot of files, but they are "simple" changes, just removing a line in a structure. Other than that, a few minor driver core and debugfs changes. There are some ath9k patches coming in through this tree that have been acked by the wireless maintainers as they relied on the debugfs changes. Everything has been in linux-next for a while" * tag 'driver-core-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (324 commits) Revert "ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries" fs: debugfs: add forward declaration for struct device type firmware class: Deletion of an unnecessary check before the function call "vunmap" firmware loader: fix hung task warning dump devcoredump: provide a one-way disable function device: Add dev_<level>_once variants ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries ath: use seq_file api for ath9k debugfs files debugfs: add helper function to create device related seq_file drivers/base: cacheinfo: remove noisy error boot message Revert "core: platform: add warning if driver has no owner" drivers: base: support cpu cache information interface to userspace via sysfs drivers: base: add cpu_device_create to support per-cpu devices topology: replace custom attribute macros with standard DEVICE_ATTR* cpumask: factor out show_cpumap into separate helper function driver core: Fix unbalanced device reference in drivers_probe driver core: fix race with userland in device_add() sysfs/kernfs: make read requests on pre-alloc files use the buffer. sysfs/kernfs: allow attributes to request write buffer be pre-allocated. fs: sysfs: return EGBIG on write if offset is larger than file size ...
2014-11-30fs: debugfs: add forward declaration for struct device typeArend van Spriel1-0/+1
The function debugfs_create_devm_seqfile() has a parameter of type struct device pointer. This type needs to be forward declared to avoid compilation issues on certain architectures and/or kernel configurations. The function was introduced with: commit 98210b7f73f1db182bd9a558a031093cd166e907 Author: Arend van Spriel <arend@broadcom.com> Date: Sun Nov 9 11:31:58 2014 +0100 debugfs: add helper function to create device related seq_file The reported build failure for sparc64 architecture was: make.cross ARCH=sparc64 All warnings: In file included from fs/debugfs/file.c:21:0: include/linux/debugfs.h:105:10: warning: 'struct device' declared inside parameter list void *data)); ^ Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Arend van Spriel <arend@broadcom.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-27debugfs: add helper function to create device related seq_fileArend van Spriel1-1/+15
This patch adds a helper function that simplifies adding a so-called single_open sequence file for device drivers. The calling device driver needs to provide a read function and a device pointer. The field struct seq_file::private will reference the device pointer upon call to the read function so the driver can obtain his data from it and do its task of providing the file content using seq_printf() calls and alike. Using this helper function also gets rid of the need to specify file operations per debugfs file. Signed-off-by: Arend van Spriel <arend@broadcom.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05debugfs: Have debugfs_print_regs32() return voidJoe Perches1-4/+3
The seq_printf() will soon just return void, and seq_has_overflowed() should be used instead to see if the seq can no longer accept input. As the return value of debugfs_print_regs32() has no users and the seq_file descriptor should be checked with seq_has_overflowed() instead of return values of functions, it is better to just have debugfs_print_regs32() also return void. Link: http://lkml.kernel.org/p/2634b19eb1c04a9d31148c1fe6f1f3819be95349.1412031505.git.joe@perches.com Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Joe Perches <joe@perches.com> [ original change only updated seq_printf() return, added return of void to debugfs_print_regs32() as well ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-10-04fs/debugfs: add declaration for no CONFIG_DEBUG_FSWeijie Yang1-0/+12
Two function declarations are absence if not define CONFIG_DEBUG_FS in include/linux/debugfs.h Signed-off-by: Weijie Yang <weijie.yang@samsung.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-28debugfs: provide debugfs_create_x64() when disabledJohannes Berg1-0/+7
commit 15b0beaa332b3923cc ("Add x64 support to debugfs") added debugfs_create_x64(), but forgot to provide it when debugfs is disabled, causing problems when code tries to use it even then. Provide the appropriate static inline. Cc: Huang Ying <ying.huang@intel.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-06-04debugfs: add get/set for atomic typesSeth Jennings1-0/+2
debugfs currently lack the ability to create attributes that set/get atomic_t values. This patch adds support for this through a new debugfs_create_atomic_t() function. Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-19debugfs: regset32: make struct debugfs_reg32 pointer constFelipe Balbi1-1/+1
no user of that should ever change that pointer, so let's mark it const to prevent that from happening. Signed-off-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-17debugfs: Add support to print u32 array in debugfsSrivatsa Vaddagiri1-0/+11
Move the code from Xen to debugfs to make the code common for other users as well. Accked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Suzuki Poulose <suzuki@in.ibm.com> [v1: Fixed rebase issues] [v2: Fixed PPC compile issues] Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-03-21debugfs-related mode_t whack-a-moleAl Viro1-2/+2
all of those should be umode_t... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-09Merge branch 'for-linus2' of ↵Linus Torvalds1-23/+23
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs * 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (165 commits) reiserfs: Properly display mount options in /proc/mounts vfs: prevent remount read-only if pending removes vfs: count unlinked inodes vfs: protect remounting superblock read-only vfs: keep list of mounts for each superblock vfs: switch ->show_options() to struct dentry * vfs: switch ->show_path() to struct dentry * vfs: switch ->show_devname() to struct dentry * vfs: switch ->show_stats to struct dentry * switch security_path_chmod() to struct path * vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb vfs: trim includes a bit switch mnt_namespace ->root to struct mount vfs: take /proc/*/mounts and friends to fs/proc_namespace.c vfs: opencode mntget() mnt_set_mountpoint() vfs: spread struct mount - remaining argument of next_mnt() vfs: move fsnotify junk to struct mount vfs: move mnt_devname vfs: move mnt_list to struct mount vfs: switch pnode.h macros to struct mount * ...
2012-01-04switch debugfs to umode_tAl Viro1-23/+23
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-11-19debugfs: print_regs32: make regs array a const pointerAlessandro Rubini1-1/+1
Signed-off-by: Alessandro Rubini <rubini@gnudd.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-11-18debugfs: add tools to printk 32-bit registersAlessandro Rubini1-0/+26
Some debugfs file I deal with are mostly blocks of registers, i.e. lines of the form "<name> = 0x<value>". Some files are only registers, some include registers blocks among other material. This patch introduces data structures and functions to deal with both cases. I expect more users of this over time. Signed-off-by: Alessandro Rubini <rubini@gnudd.com> Acked-by: Giancarlo Asnaghi <giancarlo.asnaghi@st.com> Cc: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-05-20Add x64 support to debugfsHuang Ying1-0/+2
Add debugfs_create_x64. This is needed by ACPI APEI EINJ parameters support. Signed-off-by: Huang Ying <ying.huang@intel.com> Signed-off-by: Andi Kleen <ak@linux.intel.com> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Len Brown <len.brown@intel.com>
2009-09-24docs: fix various Documentation/ paths in header filesRandy Dunlap1-1/+1
Fix various Documentation/ paths in include/linux/. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Reviewed-by: Jesper Juhl <jj@chaosbits.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-03-23debugfs: function to know if debugfs is initializedFrederic Weisbecker1-0/+8
Impact: add new debugfs API With ftrace, some tracers are registered in early initcalls and attempt to create files on the debugfs filesystem. Depending on when they are activated, they can try to create their file at any time. Some checks can be done on the tracing area but providing a helper to know if debugfs is registered make it really more easy. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <1237759847-21025-2-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-27Fix "multiple definition of `debugfs_create_size_t'"Linus Torvalds1-1/+1
Introduced by 8adb711f3668b034e7b956fac951ed08b53e0d55 ("debugfs: introduce stub for debugfs_create_size_t() when DEBUG_FS=n") and due to a simple missing "static inline". Reported-and-tested-by: Jeff Chua <jeff.chua.linux@gmail.com> Acked-by: Greg KH <gregkh@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-21debugfs: introduce stub for debugfs_create_size_t() when DEBUG_FS=nInaky Perez-Gonzalez1-0/+7
Toralf Förster <toralf.foerster@gmx.de> reported a build failure in the WiMAX stack when CONFIG_DEBUG_FS=n http://linuxwimax.org/pipermail/wimax/2009-January/000449.html This is due to debugfs_create_size_t() missing an stub that returns -ENODEV when the DEBUGFS subsystem is not configured in (like the rest of the debugfs API). This patch adds said stub. Reported-by: Toralf Förster <toralf.foerster@gmx.de> Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-01-07debugfs: add helpers for exporting a size_t simple valueInaky Perez-Gonzalez1-0/+2
In the same spirit as debugfs_create_*(), introduce helpers for exporting size_t values over debugfs. The only trick done is that the format verifier is kept at %llu instead of %zu; otherwise type warnings would pop up: format ‘%zu’ expects type ‘size_t’, but argument 2 has type ‘long long unsigned int’ There is no real way to fix this one--however, we can consider %llu and %zu to be compatible if we consider that we are using the same for validating in debugfs_create_{x,u}{8,16,32}(). Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-07-22debugfs: Implement debugfs_remove_recursive()Haavard Skinnemoen1-0/+4
debugfs_remove_recursive() will remove a dentry and all its children. Drivers can use this to zap their whole debugfs tree so that they don't need to keep track of every single debugfs dentry they created. It may fail to remove the whole tree in certain cases: sh-3.2# rmmod atmel-mci < /sys/kernel/debug/mmc0/ios/clock mmc0: card b368 removed atmel_mci atmel_mci.0: Lost dma0chan1, falling back to PIO sh-3.2# ls /sys/kernel/debug/mmc0/ ios But I'm not sure if that case can be handled in any sane manner. Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> Cc: Pierre Ossman <drzeus-list@drzeus.cx> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>