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Commit f67b1503 authored by Linus Torvalds's avatar Linus Torvalds Committed by Ingo Molnar
Browse files

perf/hwbp: Simplify the perf-hwbp code, fix documentation 



Annoyingly, modify_user_hw_breakpoint() unnecessarily complicates the
modification of a breakpoint - simplify it and remove the pointless
local variables.

Also update the stale Docbook while at it.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 71eb9ee9

kernel/events/hw_breakpoint.c

+7 −23
Original line number Diff line number Diff line
@@ -427,16 +427,9 @@ EXPORT_SYMBOL_GPL(register_user_hw_breakpoint); 
 * modify_user_hw_breakpoint - modify a user-space hardware breakpoint

 * @bp: the breakpoint structure to modify

 * @attr: new breakpoint attributes

 * @triggered: callback to trigger when we hit the breakpoint

 * @tsk: pointer to 'task_struct' of the process to which the address belongs

 */

int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr)

{

	u64 old_addr = bp->attr.bp_addr;

	u64 old_len = bp->attr.bp_len;

	int old_type = bp->attr.bp_type;

	int err = 0;



	/*

	 * modify_user_hw_breakpoint can be invoked with IRQs disabled and hence it

	 * will not be possible to raise IPIs that invoke __perf_event_disable.
@@ -451,27 +444,18 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att 
	bp->attr.bp_addr = attr->bp_addr;

	bp->attr.bp_type = attr->bp_type;

	bp->attr.bp_len = attr->bp_len;

	bp->attr.disabled = 1;



	if (attr->disabled)

		goto end;

	if (!attr->disabled) {

		int err = validate_hw_breakpoint(bp);



	err = validate_hw_breakpoint(bp);

	if (!err)

		perf_event_enable(bp);

		if (err)

			return err;



	if (err) {

		bp->attr.bp_addr = old_addr;

		bp->attr.bp_type = old_type;

		bp->attr.bp_len = old_len;

		if (!bp->attr.disabled)

		perf_event_enable(bp);



		return err;

		bp->attr.disabled = 0;

	}



end:

	bp->attr.disabled = attr->disabled;



	return 0;

}

EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);