diff options
author | Peter Rosin <peda@axentia.se> | 2018-07-20 11:39:14 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-05 10:26:29 +0300 |
commit | 0ba83f87c3f1a16dab4a55ca52c57e59486c9917 (patch) | |
tree | 83822caf9882aaaf8d39044f650396ddf4da4394 /drivers | |
parent | b3da5df23900dd092895e8d2b897d4ddc641cc8b (diff) | |
download | linux-0ba83f87c3f1a16dab4a55ca52c57e59486c9917.tar.xz |
i2c/mux, locking/core: Annotate the nested rt_mutex usage
[ Upstream commit 7b94ea50514d1a0dc94f02723b603c27bc0ea597 ]
If an i2c topology has instances of nested muxes, then a lockdep splat
is produced when when i2c_parent_lock_bus() is called. Here is an
example:
============================================
WARNING: possible recursive locking detected
--------------------------------------------
insmod/68159 is trying to acquire lock:
(i2c_register_adapter#2){+.+.}, at: i2c_parent_lock_bus+0x32/0x50 [i2c_mux]
but task is already holding lock:
(i2c_register_adapter#2){+.+.}, at: i2c_parent_lock_bus+0x32/0x50 [i2c_mux]
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(i2c_register_adapter#2);
lock(i2c_register_adapter#2);
*** DEADLOCK ***
May be due to missing lock nesting notation
1 lock held by insmod/68159:
#0: (i2c_register_adapter#2){+.+.}, at: i2c_parent_lock_bus+0x32/0x50 [i2c_mux]
stack backtrace:
CPU: 13 PID: 68159 Comm: insmod Tainted: G O
Call Trace:
dump_stack+0x67/0x98
__lock_acquire+0x162e/0x1780
lock_acquire+0xba/0x200
rt_mutex_lock+0x44/0x60
i2c_parent_lock_bus+0x32/0x50 [i2c_mux]
i2c_parent_lock_bus+0x3e/0x50 [i2c_mux]
i2c_smbus_xfer+0xf0/0x700
i2c_smbus_read_byte+0x42/0x70
my2c_init+0xa2/0x1000 [my2c]
do_one_initcall+0x51/0x192
do_init_module+0x62/0x216
load_module+0x20f9/0x2b50
SYSC_init_module+0x19a/0x1c0
SyS_init_module+0xe/0x10
do_syscall_64+0x6c/0x1a0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
Reported-by: John Sperbeck <jsperbeck@google.com>
Tested-by: John Sperbeck <jsperbeck@google.com>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Deepa Dinamani <deepadinamani@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Chang <dpf@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Wolfram Sang <wsa@the-dreams.de>
Link: http://lkml.kernel.org/r/20180720083914.1950-3-peda@axentia.se
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/i2c/i2c-core-base.c | 2 | ||||
-rw-r--r-- | drivers/i2c/i2c-mux.c | 4 |
2 files changed, 3 insertions, 3 deletions
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 6f2fe63e8f5a..7b961c9c62ef 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -638,7 +638,7 @@ static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr) static void i2c_adapter_lock_bus(struct i2c_adapter *adapter, unsigned int flags) { - rt_mutex_lock(&adapter->bus_lock); + rt_mutex_lock_nested(&adapter->bus_lock, i2c_adapter_depth(adapter)); } /** diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c index 9669ca4937b8..7ba31f6bf148 100644 --- a/drivers/i2c/i2c-mux.c +++ b/drivers/i2c/i2c-mux.c @@ -144,7 +144,7 @@ static void i2c_mux_lock_bus(struct i2c_adapter *adapter, unsigned int flags) struct i2c_mux_priv *priv = adapter->algo_data; struct i2c_adapter *parent = priv->muxc->parent; - rt_mutex_lock(&parent->mux_lock); + rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter)); if (!(flags & I2C_LOCK_ROOT_ADAPTER)) return; i2c_lock_bus(parent, flags); @@ -181,7 +181,7 @@ static void i2c_parent_lock_bus(struct i2c_adapter *adapter, struct i2c_mux_priv *priv = adapter->algo_data; struct i2c_adapter *parent = priv->muxc->parent; - rt_mutex_lock(&parent->mux_lock); + rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter)); i2c_lock_bus(parent, flags); } |