From fd0b19ed5389187829b854900511c9195875bb42 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Tue, 19 Sep 2017 22:07:18 -0700 Subject: [PATCH] MIPS: Fix perf event init Commit c311c797998c ("cpumask: make "nr_cpumask_bits" unsigned") modified mipspmu_event_init() to cast the struct perf_event cpu field to an unsigned integer before it is compared with nr_cpumask_bits (and *ahem* did so without copying the linux-mips mailing list or any MIPS developers...). This is broken because the cpu field may be -1 for events which follow a process rather than being affine to a particular CPU. When this is the case the cast to an unsigned int results in a value equal to ULONG_MAX, which is always greater than nr_cpumask_bits so we always fail mipspmu_event_init() and return -ENODEV. The check against nr_cpumask_bits seems nonsensical anyway, so this patch simply removes it. The cpu field is going to either be -1 or a valid CPU number. Comparing it with nr_cpumask_bits is effectively checking that it's a valid cpu number, but it seems safe to rely on the core perf events code to ensure that's the case. The end result is that this fixes use of perf on MIPS when not constraining events to a particular CPU, and fixes the "perf list hw" command which fails to list any events without this. Signed-off-by: Paul Burton Fixes: c311c797998c ("cpumask: make "nr_cpumask_bits" unsigned") Cc: Alexey Dobriyan Cc: Andrew Morton Cc: linux-mips@linux-mips.org Cc: stable # v4.12+ Patchwork: https://patchwork.linux-mips.org/patch/17323/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/perf_event_mipsxx.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/mips/kernel/perf_event_mipsxx.c b/arch/mips/kernel/perf_event_mipsxx.c index 9e6c74bf66c4..6668f67a61c3 100644 --- a/arch/mips/kernel/perf_event_mipsxx.c +++ b/arch/mips/kernel/perf_event_mipsxx.c @@ -618,8 +618,7 @@ static int mipspmu_event_init(struct perf_event *event) return -ENOENT; } - if ((unsigned int)event->cpu >= nr_cpumask_bits || - (event->cpu >= 0 && !cpu_online(event->cpu))) + if (event->cpu >= 0 && !cpu_online(event->cpu)) return -ENODEV; if (!atomic_inc_not_zero(&active_events)) { -- 2.45.2