Port the following patch for ARM by Mark Rutland:
-
57ce9bb39b476accf8fba6e16aea67ed76ea523d
ARM: 6902/1: perf: Remove erroneous check on active_events
When initialising a PMU, there is a check to protect against races with
other CPUs filling all of the available event slots. Since armpmu_add
checks that an event can be scheduled, we do not need to do this at
initialisation time. Furthermore the current code is broken because it
assumes that atomic_inc_not_zero will unconditionally increment
active_counts and then tries to decrement it again on failure.
This patch removes the broken, redundant code.
Signed-off-by: Deng-Cheng Zhu <dczhu@mips.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: David Daney <david.daney@cavium.com>
Cc: Eyal Barzilay <eyal@mips.com>
Cc: Zenon Fortuna <zenon@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/3106/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
return -ENODEV;
if (!atomic_inc_not_zero(&active_events)) {
- if (atomic_read(&active_events) > MIPS_MAX_HWEVENTS) {
- atomic_dec(&active_events);
- return -ENOSPC;
- }
-
mutex_lock(&pmu_reserve_mutex);
if (atomic_read(&active_events) == 0)
err = mipspmu_get_irq();