From dec2960827c85253d76938dbfa909df3be34958b Mon Sep 17 00:00:00 2001 From: Sergey Senozhatsky Date: Wed, 23 Mar 2011 14:38:28 +0200 Subject: [PATCH 1/5] lockdep: Remove unused 'factor' variable from lockdep_stats_show() Signed-off-by: Sergey Senozhatsky Cc: Peter Zijlstra LKML-Reference: <20110323123828.GB4244@swordfish.minsk.epam.com> Signed-off-by: Ingo Molnar --- kernel/lockdep_proc.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c index 1969d2fc4b36..71edd2f60c02 100644 --- a/kernel/lockdep_proc.c +++ b/kernel/lockdep_proc.c @@ -225,7 +225,7 @@ static int lockdep_stats_show(struct seq_file *m, void *v) nr_irq_read_safe = 0, nr_irq_read_unsafe = 0, nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0, nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0, - sum_forward_deps = 0, factor = 0; + sum_forward_deps = 0; list_for_each_entry(class, &all_lock_classes, lock_entry) { @@ -283,13 +283,6 @@ static int lockdep_stats_show(struct seq_file *m, void *v) nr_hardirq_unsafe * nr_hardirq_safe + nr_list_entries); - /* - * Estimated factor between direct and indirect - * dependencies: - */ - if (nr_list_entries) - factor = sum_forward_deps / nr_list_entries; - #ifdef CONFIG_PROVE_LOCKING seq_printf(m, " dependency chains: %11lu [max: %lu]\n", nr_lock_chains, MAX_LOCKDEP_CHAINS); From 0f77a8d378254f27df4a114a5da67223af1fe93f Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Thu, 24 Mar 2011 11:42:29 +0900 Subject: [PATCH 2/5] vsprintf: Introduce %pB format specifier The %pB format specifier is for stack backtrace. Its handler sprint_backtrace() does symbol lookup using (address-1) to ensure the address will not point outside of the function. If there is a tail-call to the function marked "noreturn", gcc optimized out the code after the call then causes saved return address points outside of the function (i.e. the start of the next function), so pollutes call trace somewhat. This patch adds the %pB printk mechanism that allows architecture call-trace printout functions to improve backtrace printouts. Signed-off-by: Namhyung Kim Acked-by: Steven Rostedt Acked-by: Frederic Weisbecker Cc: Linus Torvalds Cc: Andrew Morton Cc: linux-arch@vger.kernel.org LKML-Reference: <1300934550-21394-1-git-send-email-namhyung@gmail.com> Signed-off-by: Ingo Molnar --- include/linux/kallsyms.h | 7 +++++++ kernel/kallsyms.c | 44 +++++++++++++++++++++++++++++++++++++--- lib/vsprintf.c | 7 ++++++- 3 files changed, 54 insertions(+), 4 deletions(-) diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h index d8e9b3d1c23c..0df513b7a9f8 100644 --- a/include/linux/kallsyms.h +++ b/include/linux/kallsyms.h @@ -36,6 +36,7 @@ const char *kallsyms_lookup(unsigned long addr, /* Look up a kernel symbol and return it in a text buffer. */ extern int sprint_symbol(char *buffer, unsigned long address); +extern int sprint_backtrace(char *buffer, unsigned long address); /* Look up a kernel symbol and print it to the kernel messages. */ extern void __print_symbol(const char *fmt, unsigned long address); @@ -79,6 +80,12 @@ static inline int sprint_symbol(char *buffer, unsigned long addr) return 0; } +static inline int sprint_backtrace(char *buffer, unsigned long addr) +{ + *buffer = '\0'; + return 0; +} + static inline int lookup_symbol_name(unsigned long addr, char *symname) { return -ERANGE; diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 6f6d091b5757..59e879929b17 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -342,13 +342,15 @@ int lookup_symbol_attrs(unsigned long addr, unsigned long *size, } /* Look up a kernel symbol and return it in a text buffer. */ -int sprint_symbol(char *buffer, unsigned long address) +static int __sprint_symbol(char *buffer, unsigned long address, + int symbol_offset) { char *modname; const char *name; unsigned long offset, size; int len; + address += symbol_offset; name = kallsyms_lookup(address, &size, &offset, &modname, buffer); if (!name) return sprintf(buffer, "0x%lx", address); @@ -357,17 +359,53 @@ int sprint_symbol(char *buffer, unsigned long address) strcpy(buffer, name); len = strlen(buffer); buffer += len; + offset -= symbol_offset; if (modname) - len += sprintf(buffer, "+%#lx/%#lx [%s]", - offset, size, modname); + len += sprintf(buffer, "+%#lx/%#lx [%s]", offset, size, modname); else len += sprintf(buffer, "+%#lx/%#lx", offset, size); return len; } + +/** + * sprint_symbol - Look up a kernel symbol and return it in a text buffer + * @buffer: buffer to be stored + * @address: address to lookup + * + * This function looks up a kernel symbol with @address and stores its name, + * offset, size and module name to @buffer if possible. If no symbol was found, + * just saves its @address as is. + * + * This function returns the number of bytes stored in @buffer. + */ +int sprint_symbol(char *buffer, unsigned long address) +{ + return __sprint_symbol(buffer, address, 0); +} + EXPORT_SYMBOL_GPL(sprint_symbol); +/** + * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer + * @buffer: buffer to be stored + * @address: address to lookup + * + * This function is for stack backtrace and does the same thing as + * sprint_symbol() but with modified/decreased @address. If there is a + * tail-call to the function marked "noreturn", gcc optimized out code after + * the call so that the stack-saved return address could point outside of the + * caller. This function ensures that kallsyms will find the original caller + * by decreasing @address. + * + * This function returns the number of bytes stored in @buffer. + */ +int sprint_backtrace(char *buffer, unsigned long address) +{ + return __sprint_symbol(buffer, address, -1); +} + /* Look up a kernel symbol and print it to the kernel messages. */ void __print_symbol(const char *fmt, unsigned long address) { diff --git a/lib/vsprintf.c b/lib/vsprintf.c index d3023df8477f..d9e01fc3168e 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -574,7 +574,9 @@ char *symbol_string(char *buf, char *end, void *ptr, unsigned long value = (unsigned long) ptr; #ifdef CONFIG_KALLSYMS char sym[KSYM_SYMBOL_LEN]; - if (ext != 'f' && ext != 's') + if (ext == 'B') + sprint_backtrace(sym, value); + else if (ext != 'f' && ext != 's') sprint_symbol(sym, value); else kallsyms_lookup(value, NULL, NULL, NULL, sym); @@ -949,6 +951,7 @@ int kptr_restrict = 1; * - 'f' For simple symbolic function names without offset * - 'S' For symbolic direct pointers with offset * - 's' For symbolic direct pointers without offset + * - 'B' For backtraced symbolic direct pointers with offset * - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref] * - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201] * - 'M' For a 6-byte MAC address, it prints the address in the @@ -1008,6 +1011,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, /* Fallthrough */ case 'S': case 's': + case 'B': return symbol_string(buf, end, ptr, spec, *fmt); case 'R': case 'r': @@ -1279,6 +1283,7 @@ qualifier: * %ps output the name of a text symbol without offset * %pF output the name of a function pointer with its offset * %pf output the name of a function pointer without its offset + * %pB output the name of a backtrace symbol with its offset * %pR output the address range in a struct resource with decoded flags * %pr output the address range in a struct resource with raw flags * %pM output a 6-byte MAC address with colons From 71f9e59800e5ad4e6b683348424c9fe54306cd43 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Thu, 24 Mar 2011 11:42:30 +0900 Subject: [PATCH 3/5] x86, dumpstack: Use %pB format specifier for stack trace Improve noreturn function entries in call traces: Before: Call Trace: [] panic+0x8c/0x18d [] deep01+0x0/0x38 [test_panic] <--- bad [] proc_file_write+0x73/0x8d [] proc_reg_write+0x8d/0xac [] vfs_write+0xa1/0xc5 [] sys_write+0x45/0x6c [] system_call_fastpath+0x16/0x1b After: Call Trace: [] panic+0x8c/0x18d [] panic_write+0x20/0x20 [test_panic] <--- good [] proc_file_write+0x73/0x8d [] proc_reg_write+0x8d/0xac [] vfs_write+0xa1/0xc5 [] sys_write+0x45/0x6c [] system_call_fastpath+0x16/0x1b Signed-off-by: Namhyung Kim Acked-by: Frederic Weisbecker Cc: Steven Rostedt Cc: Linus Torvalds Cc: Andrew Morton LKML-Reference: <1300934550-21394-2-git-send-email-namhyung@gmail.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/dumpstack.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 999e2793590b..24d0479025f9 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -27,7 +27,7 @@ static int die_counter; void printk_address(unsigned long address, int reliable) { - printk(" [<%p>] %s%pS\n", (void *) address, + printk(" [<%p>] %s%pB\n", (void *) address, reliable ? "" : "? ", (void *) address); } From 2092e6be82ec71ecbf5a8ceeef004bbcbdb78812 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 17 Mar 2011 15:21:06 -0400 Subject: [PATCH 4/5] WARN_ON_SMP(): Allow use in if() statements on UP Both WARN_ON() and WARN_ON_SMP() should be able to be used in an if statement. if (WARN_ON_SMP(foo)) { ... } Because WARN_ON_SMP() is defined as a do { } while (0) on UP, it can not be used this way. Convert it to the same form that WARN_ON() is, even when CONFIG_SMP is off. Signed-off-by: Steven Rostedt Acked-by: Thomas Gleixner Acked-by: Peter Zijlstra Acked-by: Darren Hart Cc: Lai Jiangshan Cc: Linus Torvalds Cc: Andrew Morton LKML-Reference: <20110317192208.444147791@goodmis.org> Signed-off-by: Ingo Molnar --- include/asm-generic/bug.h | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h index c2c9ba032d46..f2d2faf4d9ae 100644 --- a/include/asm-generic/bug.h +++ b/include/asm-generic/bug.h @@ -165,10 +165,36 @@ extern void warn_slowpath_null(const char *file, const int line); #define WARN_ON_RATELIMIT(condition, state) \ WARN_ON((condition) && __ratelimit(state)) +/* + * WARN_ON_SMP() is for cases that the warning is either + * meaningless for !SMP or may even cause failures. + * This is usually used for cases that we have + * WARN_ON(!spin_is_locked(&lock)) checks, as spin_is_locked() + * returns 0 for uniprocessor settings. + * It can also be used with values that are only defined + * on SMP: + * + * struct foo { + * [...] + * #ifdef CONFIG_SMP + * int bar; + * #endif + * }; + * + * void func(struct foo *zoot) + * { + * WARN_ON_SMP(!zoot->bar); + * + * For CONFIG_SMP, WARN_ON_SMP() should act the same as WARN_ON(), + * and should be a nop and return false for uniprocessor. + * + * if (WARN_ON_SMP(x)) returns true only when CONFIG_SMP is set + * and x is true. + */ #ifdef CONFIG_SMP # define WARN_ON_SMP(x) WARN_ON(x) #else -# define WARN_ON_SMP(x) do { } while (0) +# define WARN_ON_SMP(x) ({0;}) #endif #endif From 29096202176ceaa5016a17ea2dd1aea19a4e90e2 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 17 Mar 2011 15:21:07 -0400 Subject: [PATCH 5/5] futex: Fix WARN_ON() test for UP An update of the futex code had a WARN_ON(!spin_is_locked(q->lock_ptr)) But on UP, spin_is_locked() is always false, and will trigger this warning, and even worse, it will exit the function without doing the necessary work. Converting this to a WARN_ON_SMP() fixes the problem. Reported-by: Richard Weinberger Tested-by: Richard Weinberger Signed-off-by: Steven Rostedt Acked-by: Thomas Gleixner Acked-by: Peter Zijlstra Acked-by: Darren Hart Cc: Lai Jiangshan LKML-Reference: <20110317192208.682654502@goodmis.org> Signed-off-by: Ingo Molnar --- kernel/futex.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index bda415715382..823aae3e2a96 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -782,8 +782,8 @@ static void __unqueue_futex(struct futex_q *q) { struct futex_hash_bucket *hb; - if (WARN_ON(!q->lock_ptr || !spin_is_locked(q->lock_ptr) - || plist_node_empty(&q->list))) + if (WARN_ON_SMP(!q->lock_ptr || !spin_is_locked(q->lock_ptr)) + || WARN_ON(plist_node_empty(&q->list))) return; hb = container_of(q->lock_ptr, struct futex_hash_bucket, lock);