diff options
| -rw-r--r-- | kernel/trace/ftrace.c | 76 |
1 files changed, 43 insertions, 33 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index a141d84..4d90c91 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -401,6 +401,8 @@ static void ftrace_profile_reset(struct ftrace_profile_stat *stat) int ftrace_profile_pages_init(struct ftrace_profile_stat *stat) { struct ftrace_profile_page *pg; + int functions; + int pages; int i; /* If we already allocated, do nothing */ @@ -411,22 +413,46 @@ int ftrace_profile_pages_init(struct ftrace_profile_stat *stat) if (!stat->pages) return -ENOMEM; +#ifdef CONFIG_DYNAMIC_FTRACE + functions = ftrace_update_tot_cnt; +#else + /* + * We do not know the number of functions that exist because + * dynamic tracing is what counts them. With past experience + * we have around 20K functions. That should be more than enough. + * It is highly unlikely we will execute every function in + * the kernel. + */ + functions = 20000; +#endif + pg = stat->start = stat->pages; - /* allocate 10 more pages to start */ - for (i = 0; i < 10; i++) { + pages = DIV_ROUND_UP(functions, PROFILES_PER_PAGE); + + for (i = 0; i < pages; i++) { pg->next = (void *)get_zeroed_page(GFP_KERNEL); - /* - * We only care about allocating profile_pages, if - * we failed to allocate here, hopefully we will allocate - * later. - */ if (!pg->next) - break; + goto out_free; pg = pg->next; } return 0; + + out_free: + pg = stat->start; + while (pg) { + unsigned long tmp = (unsigned long)pg; + + pg = pg->next; + free_page(tmp); + } + + free_page((unsigned long)stat->pages); + stat->pages = NULL; + stat->start = NULL; + + return -ENOMEM; } static int ftrace_profile_init_cpu(int cpu) @@ -460,7 +486,7 @@ static int ftrace_profile_init_cpu(int cpu) ftrace_profile_bits++; } - /* Preallocate a few pages */ + /* Preallocate the function profiling pages */ if (ftrace_profile_pages_init(stat) < 0) { kfree(stat->hash); stat->hash = NULL; @@ -516,24 +542,21 @@ static void ftrace_add_profile(struct ftrace_profile_stat *stat, hlist_add_head_rcu(&rec->node, &stat->hash[key]); } -/* Interrupts must be disabled calling this */ +/* + * The memory is already allocated, this simply finds a new record to use. + */ static struct ftrace_profile * -ftrace_profile_alloc(struct ftrace_profile_stat *stat, - unsigned long ip, bool alloc_safe) +ftrace_profile_alloc(struct ftrace_profile_stat *stat, unsigned long ip) { struct ftrace_profile *rec = NULL; - /* prevent recursion */ + /* prevent recursion (from NMIs) */ if (atomic_inc_return(&stat->disabled) != 1) goto out; - /* Try to always keep another page available */ - if (!stat->pages->next && alloc_safe) - stat->pages->next = (void *)get_zeroed_page(GFP_ATOMIC); - /* - * Try to find the function again since another - * task on another CPU could have added it + * Try to find the function again since an NMI + * could have added it */ rec = ftrace_find_profiled_func(stat, ip); if (rec) @@ -555,29 +578,16 @@ ftrace_profile_alloc(struct ftrace_profile_stat *stat, return rec; } -/* - * If we are not in an interrupt, or softirq and - * and interrupts are disabled and preemption is not enabled - * (not in a spinlock) then it should be safe to allocate memory. - */ -static bool ftrace_safe_to_allocate(void) -{ - return !in_interrupt() && irqs_disabled() && !preempt_count(); -} - static void function_profile_call(unsigned long ip, unsigned long parent_ip) { struct ftrace_profile_stat *stat; struct ftrace_profile *rec; unsigned long flags; - bool alloc_safe; if (!ftrace_profile_enabled) return; - alloc_safe = ftrace_safe_to_allocate(); - local_irq_save(flags); stat = &__get_cpu_var(ftrace_profile_stats); @@ -586,7 +596,7 @@ function_profile_call(unsigned long ip, unsigned long parent_ip) rec = ftrace_find_profiled_func(stat, ip); if (!rec) { - rec = ftrace_profile_alloc(stat, ip, alloc_safe); + rec = ftrace_profile_alloc(stat, ip); if (!rec) goto out; } |
