perf core: Generalize max_stack sysctl handler (a831100a) · Commits · 戴 / test

So that it can be used for other stack related knobs, such as the upcoming one to tweak the max number of of contexts per stack sample. In all those cases we can only change the value if there are no perf sessions collecting stacks, so they need to grab that mutex, etc. Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-8t3fk94wuzp8m2z1n4gc0s17@git.kernel.org Signed-off-by:

Arnaldo Carvalho de Melo <acme@redhat.com>

kernel/events/callchain.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -228,7 +228,8 @@ exit_put:
		int perf_event_max_stack_handler(struct ctl_table *table, int write,
		void __user buffer, size_t lenp, loff_t *ppos)
		{
		int new_value = sysctl_perf_event_max_stack, ret;
		int *value = table->data;
		int new_value = *value, ret;
		struct ctl_table new_table = *table;

		new_table.data = &new_value;
		@@ -240,7 +241,7 @@ int perf_event_max_stack_handler(struct ctl_table *table, int write,
		if (atomic_read(&nr_callchain_events))
		ret = -EBUSY;
		else
		sysctl_perf_event_max_stack = new_value;
		*value = new_value;

		mutex_unlock(&callchain_mutex);

kernel/sysctl.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1149,7 +1149,7 @@ static struct ctl_table kern_table[] = {
		},
		{
		.procname = "perf_event_max_stack",
		.data = NULL, /* filled in by handler */
		.data = &sysctl_perf_event_max_stack,
		.maxlen = sizeof(sysctl_perf_event_max_stack),
		.mode = 0644,
		.proc_handler = perf_event_max_stack_handler,

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