From 9eeba6138cefc0435695463ddadb0d95e0a6bcd2 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Sat, 11 Apr 2009 03:17:17 +0200 Subject: lockdep: warn about lockdep disabling after kernel taint Impact: provide useful missing info for developers Kernel taint can occur in several situations such as warnings, load of prorietary or staging modules, bad page, etc... But when such taint happens, a developer might still be working on the kernel, expecting that lockdep is still enabled. But a taint disables lockdep without ever warning about it. Such a kernel behaviour doesn't really help for kernel development. This patch adds this missing warning. Since the taint is done most of the time after the main message that explain the real source issue, it seems safe to warn about it inside add_taint() so that it appears at last, without hurting the main information. v2: Use a generic helper to disable lockdep instead of an open coded xchg(). Signed-off-by: Frederic Weisbecker Cc: Peter Zijlstra LKML-Reference: <1239412638-6739-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- kernel/panic.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index 3fd8c5bf8b3..940ca14f6db 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -213,8 +213,14 @@ unsigned long get_taint(void) void add_taint(unsigned flag) { - /* can't trust the integrity of the kernel anymore: */ - debug_locks = 0; + /* + * Can't trust the integrity of the kernel anymore. + * We don't call directly debug_locks_off() because the issue + * is not necessarily serious enough to set oops_in_progress to 1 + */ + if (__debug_locks_off()) + printk(KERN_WARNING "Disabling lockdep due to kernel taint\n"); + set_bit(flag, &tainted_mask); } EXPORT_SYMBOL(add_taint); -- cgit v1.2.3-70-g09d2 From 574bbe782057fdf0490dc7dec906a2dc26363e20 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Sat, 11 Apr 2009 03:17:18 +0200 Subject: lockdep: continue lock debugging despite some taints Impact: broaden lockdep checks Lockdep is disabled after any kernel taints. This might be convenient to ignore bad locking issues which sources come from outside the kernel tree. Nevertheless, it might be a frustrating experience for the staging developers or those who experience a warning but are focused on another things that require lockdep. The v2 of this patch simply don't disable anymore lockdep in case of TAINT_CRAP and TAINT_WARN events. Signed-off-by: Frederic Weisbecker Cc: LTP Cc: Peter Zijlstra Cc: Greg KH LKML-Reference: <1239412638-6739-2-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- kernel/panic.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index 940ca14f6db..934fb377f4b 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -217,8 +217,10 @@ void add_taint(unsigned flag) * Can't trust the integrity of the kernel anymore. * We don't call directly debug_locks_off() because the issue * is not necessarily serious enough to set oops_in_progress to 1 + * Also we want to keep up lockdep for staging development and + * post-warning case. */ - if (__debug_locks_off()) + if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off()) printk(KERN_WARNING "Disabling lockdep due to kernel taint\n"); set_bit(flag, &tainted_mask); -- cgit v1.2.3-70-g09d2 From b48ccb095a0c9257241261ec2bd1cbb1bdabc48b Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 23 Apr 2009 09:36:52 +0200 Subject: locking: clarify kernel-taint warning message Andi Kleen reported this message triggering on non-lockdep kernels: Disabling lockdep due to kernel taint Clarify the message to say 'lock debugging' - debug_locks_off() turns off all things lock debugging, not just lockdep. [ Impact: change kernel warning message text ] Reported-by: Andi Kleen Cc: Peter Zijlstra Cc: Andrew Morton Signed-off-by: Ingo Molnar --- kernel/panic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index 934fb377f4b..3dcaa166135 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -221,7 +221,7 @@ void add_taint(unsigned flag) * post-warning case. */ if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off()) - printk(KERN_WARNING "Disabling lockdep due to kernel taint\n"); + printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n"); set_bit(flag, &tainted_mask); } -- cgit v1.2.3-70-g09d2 From 57adc4d2dbf968fdbe516359688094eef4d46581 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 6 May 2009 16:02:53 -0700 Subject: Eliminate thousands of warnings with gcc 3.2 build When building with gcc 3.2 I get thousands of warnings such as include/linux/gfp.h: In function `allocflags_to_migratetype': include/linux/gfp.h:105: warning: null format string due to passing a NULL format string to warn_slowpath() in #define __WARN() warn_slowpath(__FILE__, __LINE__, NULL) Split this case out into a separate call. This also shrinks the kernel slightly: text data bss dec hex filename 4802274 707668 712704 6222646 5ef336 vmlinux text data bss dec hex filename 4799027 703572 712704 6215303 5ed687 vmlinux due to removeing one argument from the commonly-called __WARN(). [akpm@linux-foundation.org: reduce scope of `empty'] Acked-by: Jesper Nilsson Acked-by: Johannes Weiner Acked-by: Arjan van de Ven Signed-off-by: Andi Kleen Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-generic/bug.h | 7 ++++--- kernel/panic.c | 13 ++++++++++--- 2 files changed, 14 insertions(+), 6 deletions(-) (limited to 'kernel/panic.c') diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h index e727fe0d145..4b6755984d2 100644 --- a/include/asm-generic/bug.h +++ b/include/asm-generic/bug.h @@ -58,12 +58,13 @@ struct bug_entry { */ #ifndef __WARN #ifndef __ASSEMBLY__ -extern void warn_slowpath(const char *file, const int line, +extern void warn_slowpath_fmt(const char *file, const int line, const char *fmt, ...) __attribute__((format(printf, 3, 4))); +extern void warn_slowpath_null(const char *file, const int line); #define WANT_WARN_ON_SLOWPATH #endif -#define __WARN() warn_slowpath(__FILE__, __LINE__, NULL) -#define __WARN_printf(arg...) warn_slowpath(__FILE__, __LINE__, arg) +#define __WARN() warn_slowpath_null(__FILE__, __LINE__) +#define __WARN_printf(arg...) warn_slowpath_fmt(__FILE__, __LINE__, arg) #else #define __WARN_printf(arg...) do { printk(arg); __WARN(); } while (0) #endif diff --git a/kernel/panic.c b/kernel/panic.c index 3dcaa166135..874ecf1307a 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -340,7 +340,7 @@ void oops_exit(void) } #ifdef WANT_WARN_ON_SLOWPATH -void warn_slowpath(const char *file, int line, const char *fmt, ...) +void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) { va_list args; char function[KSYM_SYMBOL_LEN]; @@ -356,7 +356,7 @@ void warn_slowpath(const char *file, int line, const char *fmt, ...) if (board) printk(KERN_WARNING "Hardware name: %s\n", board); - if (fmt) { + if (*fmt) { va_start(args, fmt); vprintk(fmt, args); va_end(args); @@ -367,7 +367,14 @@ void warn_slowpath(const char *file, int line, const char *fmt, ...) print_oops_end_marker(); add_taint(TAINT_WARN); } -EXPORT_SYMBOL(warn_slowpath); +EXPORT_SYMBOL(warn_slowpath_fmt); + +void warn_slowpath_null(const char *file, int line) +{ + static const char *empty = ""; + warn_slowpath_fmt(file, line, empty); +} +EXPORT_SYMBOL(warn_slowpath_null); #endif #ifdef CONFIG_CC_STACKPROTECTOR -- cgit v1.2.3-70-g09d2 From 0f6f49a8cd0163fdb1723ed29f01fc65177108dc Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 May 2009 13:41:28 -0700 Subject: Fix caller information for warn_slowpath_null Ian Campbell noticed that since "Eliminate thousands of warnings with gcc 3.2 build" (commit 57adc4d2dbf968fdbe516359688094eef4d46581) all WARN_ON()'s currently appear to come from warn_slowpath_null(), eg: WARNING: at kernel/softirq.c:143 warn_slowpath_null+0x1c/0x20() because now that warn_slowpath_null() is in the call path, the __builtin_return_address(0) returns that, rather than the place that caused the warning. Fix this by splitting up the warn_slowpath_null/fmt cases differently, using a common helper function, and getting the return address in the right place. This also happens to avoid the unnecessary stack usage for the non-stdargs case, and just generally cleans things up. Make the function name printout use %pS while at it. Cc: Ian Campbell Cc: Jesper Nilsson Cc: Johannes Weiner Cc: Arjan van de Ven Cc: Andi Kleen Cc: Hugh Dickins Cc: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/panic.c | 35 ++++++++++++++++++++--------------- 1 file changed, 20 insertions(+), 15 deletions(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index 874ecf1307a..984b3ecbd72 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -340,39 +340,44 @@ void oops_exit(void) } #ifdef WANT_WARN_ON_SLOWPATH -void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) -{ +struct slowpath_args { + const char *fmt; va_list args; - char function[KSYM_SYMBOL_LEN]; - unsigned long caller = (unsigned long)__builtin_return_address(0); - const char *board; +}; - sprint_symbol(function, caller); +static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args) +{ + const char *board; printk(KERN_WARNING "------------[ cut here ]------------\n"); - printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file, - line, function); + printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); board = dmi_get_system_info(DMI_PRODUCT_NAME); if (board) printk(KERN_WARNING "Hardware name: %s\n", board); - if (*fmt) { - va_start(args, fmt); - vprintk(fmt, args); - va_end(args); - } + if (args) + vprintk(args->fmt, args->args); print_modules(); dump_stack(); print_oops_end_marker(); add_taint(TAINT_WARN); } + +void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) +{ + struct slowpath_args args; + + args.fmt = fmt; + va_start(args.args, fmt); + warn_slowpath_common(file, line, __builtin_return_address(0), &args); + va_end(args.args); +} EXPORT_SYMBOL(warn_slowpath_fmt); void warn_slowpath_null(const char *file, int line) { - static const char *empty = ""; - warn_slowpath_fmt(file, line, empty); + warn_slowpath_common(file, line, __builtin_return_address(0), NULL); } EXPORT_SYMBOL(warn_slowpath_null); #endif -- cgit v1.2.3-70-g09d2