Commit-ID: 3d9a8072915366b5932beeed97f158f8d4955768 Gitweb: https://git.kernel.org/tip/3d9a8072915366b5932beeed97f158f8d4955768 Author: Thomas Gleixner <[email protected]> AuthorDate: Thu, 25 Apr 2019 11:44:54 +0200 Committer: Thomas Gleixner <[email protected]> CommitDate: Mon, 29 Apr 2019 12:37:46 +0200
tracing: Cleanup stack trace code - Remove the extra array member of stack_dump_trace[] along with the ARRAY_SIZE - 1 initialization for struct stack_trace :: max_entries. Both are historical leftovers of no value. The stack tracer never exceeds the array and there is no extra storage requirement either. - Make variables which are only used in trace_stack.c static. - Simplify the enable/disable logic. - Rename stack_trace_print() as it's using the stack_trace_ namespace. Free the name up for stack trace related functions. Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Steven Rostedt <[email protected]> Reviewed-by: Josh Poimboeuf <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Alexander Potapenko <[email protected]> Cc: Alexey Dobriyan <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: [email protected] Cc: David Rientjes <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: [email protected] Cc: Mike Rapoport <[email protected]> Cc: Akinobu Mita <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: [email protected] Cc: Robin Murphy <[email protected]> Cc: Marek Szyprowski <[email protected]> Cc: Johannes Thumshirn <[email protected]> Cc: David Sterba <[email protected]> Cc: Chris Mason <[email protected]> Cc: Josef Bacik <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Mike Snitzer <[email protected]> Cc: Alasdair Kergon <[email protected]> Cc: Daniel Vetter <[email protected]> Cc: [email protected] Cc: Joonas Lahtinen <[email protected]> Cc: Maarten Lankhorst <[email protected]> Cc: [email protected] Cc: David Airlie <[email protected]> Cc: Jani Nikula <[email protected]> Cc: Rodrigo Vivi <[email protected]> Cc: Tom Zanussi <[email protected]> Cc: Miroslav Benes <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected] --- include/linux/ftrace.h | 18 ++++-------------- kernel/trace/trace_stack.c | 42 +++++++++++++----------------------------- 2 files changed, 17 insertions(+), 43 deletions(-) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 730876187344..20899919ead8 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -241,21 +241,11 @@ static inline void ftrace_free_mem(struct module *mod, void *start, void *end) { #ifdef CONFIG_STACK_TRACER -#define STACK_TRACE_ENTRIES 500 - -struct stack_trace; - -extern unsigned stack_trace_index[]; -extern struct stack_trace stack_trace_max; -extern unsigned long stack_trace_max_size; -extern arch_spinlock_t stack_trace_max_lock; - extern int stack_tracer_enabled; -void stack_trace_print(void); -int -stack_trace_sysctl(struct ctl_table *table, int write, - void __user *buffer, size_t *lenp, - loff_t *ppos); + +int stack_trace_sysctl(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos); /* DO NOT MODIFY THIS VARIABLE DIRECTLY! */ DECLARE_PER_CPU(int, disable_stack_tracer); diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index c6e54ff25cae..4efda5f75a0f 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -18,30 +18,26 @@ #include "trace.h" -static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES + 1]; -unsigned stack_trace_index[STACK_TRACE_ENTRIES]; +#define STACK_TRACE_ENTRIES 500 + +static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES]; +static unsigned stack_trace_index[STACK_TRACE_ENTRIES]; -/* - * Reserve one entry for the passed in ip. This will allow - * us to remove most or all of the stack size overhead - * added by the stack tracer itself. - */ struct stack_trace stack_trace_max = { - .max_entries = STACK_TRACE_ENTRIES - 1, + .max_entries = STACK_TRACE_ENTRIES, .entries = &stack_dump_trace[0], }; -unsigned long stack_trace_max_size; -arch_spinlock_t stack_trace_max_lock = +static unsigned long stack_trace_max_size; +static arch_spinlock_t stack_trace_max_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; DEFINE_PER_CPU(int, disable_stack_tracer); static DEFINE_MUTEX(stack_sysctl_mutex); int stack_tracer_enabled; -static int last_stack_tracer_enabled; -void stack_trace_print(void) +static void print_max_stack(void) { long i; int size; @@ -61,16 +57,7 @@ void stack_trace_print(void) } } -/* - * When arch-specific code overrides this function, the following - * data should be filled up, assuming stack_trace_max_lock is held to - * prevent concurrent updates. - * stack_trace_index[] - * stack_trace_max - * stack_trace_max_size - */ -void __weak -check_stack(unsigned long ip, unsigned long *stack) +static void check_stack(unsigned long ip, unsigned long *stack) { unsigned long this_size, flags; unsigned long *p, *top, *start; static int tracer_frame; @@ -179,7 +166,7 @@ check_stack(unsigned long ip, unsigned long *stack) stack_trace_max.nr_entries = x; if (task_stack_end_corrupted(current)) { - stack_trace_print(); + print_max_stack(); BUG(); } @@ -412,23 +399,21 @@ stack_trace_sysctl(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { + int was_enabled; int ret; mutex_lock(&stack_sysctl_mutex); + was_enabled = !!stack_tracer_enabled; ret = proc_dointvec(table, write, buffer, lenp, ppos); - if (ret || !write || - (last_stack_tracer_enabled == !!stack_tracer_enabled)) + if (ret || !write || (was_enabled == !!stack_tracer_enabled)) goto out; - last_stack_tracer_enabled = !!stack_tracer_enabled; - if (stack_tracer_enabled) register_ftrace_function(&trace_ops); else unregister_ftrace_function(&trace_ops); - out: mutex_unlock(&stack_sysctl_mutex); return ret; @@ -444,7 +429,6 @@ static __init int enable_stacktrace(char *str) strncpy(stack_trace_filter_buf, str + len, COMMAND_LINE_SIZE); stack_tracer_enabled = 1; - last_stack_tracer_enabled = 1; return 1; } __setup("stacktrace", enable_stacktrace);
