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Patch "perf/hwbp: Simplify the perf-hwbp code, fix documentation" has been added to the 4.14-stable tree

PATCH [email protected] 1 participant 1 message Apr 1, 2018

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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 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
perf-hwbp-simplify-the-perf-hwbp-code-fix-documentation.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From f67b15037a7a50c57f72e69a6d59941ad90a0f0f Mon Sep 17 00:00:00 2001

From: Linus Torvalds <[email protected]>
Date: Mon, 26 Mar 2018 15:39:07 -1000
Subject: perf/hwbp: Simplify the perf-hwbp code, fix documentation

From: Linus Torvalds <[email protected]>

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 <[email protected]>
Acked-by Thomas Gleixner <[email protected]>
Cc <[email protected]>
Cc Alexander Shishkin <[email protected]>
Cc Andy Lutomirski <[email protected]>
Cc Arnaldo Carvalho de Melo <[email protected]>
Cc Frederic Weisbecker <[email protected]>
Cc Jiri Olsa <[email protected]>
Cc Peter Zijlstra <[email protected]>
Cc Stephane Eranian <[email protected]>
Cc Vince Weaver <[email protected]>
Signed-off-by Ingo Molnar <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 kernel/events/hw_breakpoint.c |   30 +++++++-----------------------
 1 file changed, 7 insertions(+), 23 deletions(-)
kernel/events/hw_breakpoint.c +7 -23
@@ -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 [email protected] are

queue-4.14/perf-hwbp-simplify-the-perf-hwbp-code-fix-documentation.patch queue-4.14/ipc-shm.c-add-split-function-to-shm_vm_ops.patch