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| author | Oleg Nesterov <oleg@redhat.com> | 2013-06-20 17:50:11 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-06-20 17:58:55 +0200 |
| commit | e1ebe86203e6532eb5a0ae8f26ccae47aca548ae (patch) | |
| tree | dc9464fa0779f4d45d79f360192a8cf533bb90aa /kernel/events | |
| parent | f070a4dba984975f6353c6f1d966da1a6ce4b86f (diff) | |
| download | linux-e1ebe86203e6532eb5a0ae8f26ccae47aca548ae.tar.gz linux-e1ebe86203e6532eb5a0ae8f26ccae47aca548ae.tar.bz2 linux-e1ebe86203e6532eb5a0ae8f26ccae47aca548ae.zip | |
hw_breakpoint: Simplify list/idx mess in toggle_bp_slot() paths
The enable/disable logic in toggle_bp_slot() is not symmetrical
and imho very confusing. "old_count" in toggle_bp_task_slot() is
actually new_count because this bp was already removed from the
list.
Change toggle_bp_slot() to always call list_add/list_del after
toggle_bp_task_slot(). This way old_idx is task_bp_pinned() and
this entry should be decremented, new_idx is +/-weight and we
need to increment this element. The code/logic looks obvious.
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20130620155011.GA6330@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/hw_breakpoint.c | 40 |
1 files changed, 16 insertions, 24 deletions
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index ef8ebe560949..dee0148dcf54 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -185,26 +185,20 @@ fetch_this_slot(struct bp_busy_slots *slots, int weight) static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable, enum bp_type_idx type, int weight) { - unsigned int *tsk_pinned; - int old_count = 0; - int old_idx = 0; - int idx = 0; - - old_count = task_bp_pinned(cpu, bp, type); - old_idx = old_count - 1; - idx = old_idx + weight; - - /* tsk_pinned[n] is the number of tasks having n breakpoints */ - tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); - if (enable) { - tsk_pinned[idx]++; - if (old_count > 0) - tsk_pinned[old_idx]--; - } else { - tsk_pinned[idx]--; - if (old_count > 0) - tsk_pinned[old_idx]++; - } + /* tsk_pinned[n-1] is the number of tasks having n>0 breakpoints */ + unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); + int old_idx, new_idx; + + old_idx = task_bp_pinned(cpu, bp, type) - 1; + if (enable) + new_idx = old_idx + weight; + else + new_idx = old_idx - weight; + + if (old_idx >= 0) + tsk_pinned[old_idx]--; + if (new_idx >= 0) + tsk_pinned[new_idx]++; } /* @@ -228,10 +222,6 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type, } /* Pinned counter task profiling */ - - if (!enable) - list_del(&bp->hw.bp_list); - if (cpu >= 0) { toggle_bp_task_slot(bp, cpu, enable, type, weight); } else { @@ -241,6 +231,8 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type, if (enable) list_add_tail(&bp->hw.bp_list, &bp_task_head); + else + list_del(&bp->hw.bp_list); } /* |