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Commit a831100a authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

perf core: Generalize max_stack sysctl handler 

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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 0a77582f

kernel/events/callchain.c

+3 −2
Original line number Diff line number Diff line
@@ -228,7 +228,8 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user, 
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,