This is a note to let you know that I've just added the patch titled

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

to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: perf-hwbp-simplify-the-perf-hwbp-code-fix-documentation.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From f67b15037a7a50c57f72e69a6d59941ad90a0f0f Mon Sep 17 00:00:00 2001

From: Linus Torvalds torvalds@linux-foundation.org Date: Mon, 26 Mar 2018 15:39:07 -1000 Subject: perf/hwbp: Simplify the perf-hwbp code, fix documentation

From: Linus Torvalds torvalds@linux-foundation.org

commit f67b15037a7a50c57f72e69a6d59941ad90a0f0f upstream.

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: Linus Torvalds torvalds@linux-foundation.org Acked-by: Thomas 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: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- kernel/events/hw_breakpoint.c | 30 +++++++----------------------- 1 file changed, 7 insertions(+), 23 deletions(-)

--- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -427,16 +427,9 @@ EXPORT_SYMBOL_GPL(register_user_hw_break * 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 per 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; - - err = validate_hw_breakpoint(bp); - if (!err) - perf_event_enable(bp); + if (!attr->disabled) { + int err = validate_hw_breakpoint(bp);

- 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); + if (err) + return err;

- return err; + perf_event_enable(bp); + bp->attr.disabled = 0; }

-end: - bp->attr.disabled = attr->disabled; - return 0; } EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);

Patches currently in stable-queue which might be from torvalds@linux-foundation.org are

queue-4.15/perf-hwbp-simplify-the-perf-hwbp-code-fix-documentation.patch queue-4.15/ipc-shm.c-add-split-function-to-shm_vm_ops.patch