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

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: 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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 609e120..eeb84bb 100644 (file)
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -443,16 +443,9 @@ 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
  * 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)
 {
  */
 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.
        /*
         * 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.


@@ -467,27 +460,18 @@ 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.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);
        return 0;
 }
 EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);