From 239a5791ffd5559f51815df442c4dbbe7fc21ade Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 10 Feb 2020 13:11:42 -0800 Subject: dynamic_debug: allow to work if debugfs is disabled With the realization that having debugfs enabled on "production" systems is generally not a good idea, debugfs is being disabled from more and more platforms over time. However, the functionality of dynamic debugging still is needed at times, and since it relies on debugfs for its user api, having debugfs disabled also forces dynamic debug to be disabled. To get around this, also create the "control" file for dynamic_debug in procfs. This allows people turn on debugging as needed at runtime for individual driverfs and subsystems. Reported-by: many different companies Cc: Jason Baron Acked-by: Will Deacon Link: https://lore.kernel.org/r/20200210211142.GB1373304@kroah.com Signed-off-by: Greg Kroah-Hartman --- lib/Kconfig.debug | 7 ++++--- lib/dynamic_debug.c | 28 +++++++++++++++++++++++----- 2 files changed, 27 insertions(+), 8 deletions(-) (limited to 'lib') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 69def4a9df00..7f4992fd8a2e 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -98,7 +98,7 @@ config DYNAMIC_DEBUG bool "Enable dynamic printk() support" default n depends on PRINTK - depends on DEBUG_FS + depends on (DEBUG_FS || PROC_FS) help Compiles debug level messages into the kernel, which would not @@ -116,8 +116,9 @@ config DYNAMIC_DEBUG Usage: Dynamic debugging is controlled via the 'dynamic_debug/control' file, - which is contained in the 'debugfs' filesystem. Thus, the debugfs - filesystem must first be mounted before making use of this feature. + which is contained in the 'debugfs' filesystem or procfs. + Thus, the debugfs or procfs filesystem must first be mounted before + making use of this feature. We refer the control file as: /dynamic_debug/control. This file contains a list of the debug statements that can be enabled. The format for each line of the file is: diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index c60409138e13..aae17d9522e5 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -876,6 +876,14 @@ static const struct file_operations ddebug_proc_fops = { .write = ddebug_proc_write }; +static const struct proc_ops proc_fops = { + .proc_open = ddebug_proc_open, + .proc_read = seq_read, + .proc_lseek = seq_lseek, + .proc_release = seq_release_private, + .proc_write = ddebug_proc_write +}; + /* * Allocate a new ddebug_table for the given module * and add it to the global list. @@ -991,15 +999,25 @@ static void ddebug_remove_all_tables(void) static __initdata int ddebug_init_success; -static int __init dynamic_debug_init_debugfs(void) +static int __init dynamic_debug_init_control(void) { - struct dentry *dir; + struct proc_dir_entry *procfs_dir; + struct dentry *debugfs_dir; if (!ddebug_init_success) return -ENODEV; - dir = debugfs_create_dir("dynamic_debug", NULL); - debugfs_create_file("control", 0644, dir, NULL, &ddebug_proc_fops); + /* Create the control file in debugfs if it is enabled */ + if (debugfs_initialized()) { + debugfs_dir = debugfs_create_dir("dynamic_debug", NULL); + debugfs_create_file("control", 0644, debugfs_dir, NULL, + &ddebug_proc_fops); + } + + /* Also create the control file in procfs */ + procfs_dir = proc_mkdir("dynamic_debug", NULL); + if (procfs_dir) + proc_create("control", 0644, procfs_dir, &proc_fops); return 0; } @@ -1077,4 +1095,4 @@ out_err: early_initcall(dynamic_debug_init); /* Debugfs setup must be done later */ -fs_initcall(dynamic_debug_init_debugfs); +fs_initcall(dynamic_debug_init_control); -- cgit v1.2.3