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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: 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>
This commit is contained in:
Linus Torvalds 2018-03-26 15:39:07 -10:00 committed by Ingo Molnar
parent 71eb9ee959
commit f67b15037a
1 changed files with 7 additions and 23 deletions
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30
kernel/events/hw_breakpoint.c
View File

@ -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.
@ -451,26 +444,17 @@ 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;
err = validate_hw_breakpoint(bp);
if (!err)
perf_event_enable(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 (!attr->disabled) {
int err = validate_hw_breakpoint(bp);
if (err)
return err;
}
end:
bp->attr.disabled = attr->disabled;
perf_event_enable(bp);
bp->attr.disabled = 0;
}
return 0;
}