diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b90a827a4641b0a53de7dd3203a039a71b3b7ad2..88111b08b2c1d6885c703d3322b274ba425b4db3 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -77,6 +77,13 @@ static int dummy_set_flag(u32 old_flags, u32 bit, int set) return 0; } +/* + * To prevent the comm cache from being overwritten when no + * tracing is active, only save the comm when a trace event + * occurred. + */ +static DEFINE_PER_CPU(bool, trace_cmdline_save); + /* * Kill all tracing for good (never come back). * It is initialized to 1 but will turn to zero if the initialization @@ -1135,6 +1142,11 @@ void tracing_record_cmdline(struct task_struct *tsk) !tracing_is_on()) return; + if (!__this_cpu_read(trace_cmdline_save)) + return; + + __this_cpu_write(trace_cmdline_save, false); + trace_save_cmdline(tsk); } @@ -1178,13 +1190,20 @@ trace_buffer_lock_reserve(struct ring_buffer *buffer, return event; } +void +__buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event) +{ + __this_cpu_write(trace_cmdline_save, true); + ring_buffer_unlock_commit(buffer, event); +} + static inline void __trace_buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event, unsigned long flags, int pc, int wake) { - ring_buffer_unlock_commit(buffer, event); + __buffer_unlock_commit(buffer, event); ftrace_trace_stack(buffer, flags, 6, pc); ftrace_trace_userstack(buffer, flags, pc); @@ -1232,7 +1251,7 @@ void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer, unsigned long flags, int pc, struct pt_regs *regs) { - ring_buffer_unlock_commit(buffer, event); + __buffer_unlock_commit(buffer, event); ftrace_trace_stack_regs(buffer, flags, 0, pc, regs); ftrace_trace_userstack(buffer, flags, pc); @@ -1269,7 +1288,7 @@ trace_function(struct trace_array *tr, entry->parent_ip = parent_ip; if (!filter_check_discard(call, entry, buffer, event)) - ring_buffer_unlock_commit(buffer, event); + __buffer_unlock_commit(buffer, event); } void @@ -1362,7 +1381,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer, entry->size = trace.nr_entries; if (!filter_check_discard(call, entry, buffer, event)) - ring_buffer_unlock_commit(buffer, event); + __buffer_unlock_commit(buffer, event); out: /* Again, don't let gcc optimize things here */ @@ -1458,7 +1477,7 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc) save_stack_trace_user(&trace); if (!filter_check_discard(call, entry, buffer, event)) - ring_buffer_unlock_commit(buffer, event); + __buffer_unlock_commit(buffer, event); out_drop_count: __this_cpu_dec(user_stack_count); @@ -1653,7 +1672,7 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args) memcpy(entry->buf, tbuffer, sizeof(u32) * len); if (!filter_check_discard(call, entry, buffer, event)) { - ring_buffer_unlock_commit(buffer, event); + __buffer_unlock_commit(buffer, event); ftrace_trace_stack(buffer, flags, 6, pc); } @@ -1724,7 +1743,7 @@ int trace_array_vprintk(struct trace_array *tr, memcpy(&entry->buf, tbuffer, len); entry->buf[len] = '\0'; if (!filter_check_discard(call, entry, buffer, event)) { - ring_buffer_unlock_commit(buffer, event); + __buffer_unlock_commit(buffer, event); ftrace_trace_stack(buffer, flags, 6, pc); } out: @@ -3993,7 +4012,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, } else entry->buf[cnt] = '\0'; - ring_buffer_unlock_commit(buffer, event); + __buffer_unlock_commit(buffer, event); written = cnt; diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 7824a55bd3fcc43f72adb6737af94da40c56b1e8..839ae003a053345ccc76239d464ae5c9177709c3 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -359,6 +359,9 @@ struct trace_entry *tracing_get_trace_entry(struct trace_array *tr, struct trace_entry *trace_find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts); +void __buffer_unlock_commit(struct ring_buffer *buffer, + struct ring_buffer_event *event); + int trace_empty(struct trace_iterator *iter); void *trace_find_next_entry_inc(struct trace_iterator *iter); diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c index bd3e0eef4eaacfa71fe69d09483e1ad6a1afa27b..95e96842ed291584e7f6eb592069fbcaf8700891 100644 --- a/kernel/trace/trace_branch.c +++ b/kernel/trace/trace_branch.c @@ -77,7 +77,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect) entry->correct = val == expect; if (!filter_check_discard(call, entry, buffer, event)) - ring_buffer_unlock_commit(buffer, event); + __buffer_unlock_commit(buffer, event); out: atomic_dec(&tr->data[cpu]->disabled); diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index a84b55879bc482baddfd1d58632bd80d6f5e0d52..4edb4b74eb7e75ba171240882b20ee14fbb41099 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -223,7 +223,7 @@ int __trace_graph_entry(struct trace_array *tr, entry = ring_buffer_event_data(event); entry->graph_ent = *trace; if (!filter_current_check_discard(buffer, call, entry, event)) - ring_buffer_unlock_commit(buffer, event); + __buffer_unlock_commit(buffer, event); return 1; } @@ -327,7 +327,7 @@ void __trace_graph_return(struct trace_array *tr, entry = ring_buffer_event_data(event); entry->ret = *trace; if (!filter_current_check_discard(buffer, call, entry, event)) - ring_buffer_unlock_commit(buffer, event); + __buffer_unlock_commit(buffer, event); } void trace_graph_return(struct ftrace_graph_ret *trace)