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authorVineet Gupta <vgupta@synopsys.com>2020-10-22 03:16:22 -0700
committerVineet Gupta <vgupta@synopsys.com>2020-10-22 10:57:58 -0700
commit8c42a5c02bec6c7eccf08957be3c6c8fccf9790b (patch)
treebaaec812df674806c3e7e1f6ce5e3e4534a5b997 /arch/arc/kernel
parent6364d1b41cc382db3b03cf33c57b6007ee8f09cf (diff)
ARC: perf: redo the pct irq missing in device-tree handling
commit feb92d7d3813456c11dce21 "(ARC: perf: don't bail setup if pct irq missing in device-tree)" introduced a silly brown-paper bag bug: The assignment and comparison in an if statement were not bracketed correctly leaving the order of evaluation undefined. | | if (has_interrupts && (irq = platform_get_irq(pdev, 0) >= 0)) { | ^^^ ^^^^ And given such a chance, the compiler will bite you hard, fully entitled to generating this piece of beauty: | | # if (has_interrupts && (irq = platform_get_irq(pdev, 0) >= 0)) { | | bl.d @platform_get_irq <-- irq returned in r0 | | setge r2, r0, 0 <-- r2 is bool 1 or 0 if irq >= 0 true/false | brlt.d r0, 0, @.L114 | | st_s r2,[sp] <-- irq saved is bool 1 or 0, not actual return val | st 1,[r3,160] # arc_pmu.18_29->irq <-- drops bool and assumes 1 | | # return __request_percpu_irq(irq, handler, 0, | | bl.d @__request_percpu_irq; | mov_s r0,1 <-- drops even bool and assumes 1 which fails With the snafu fixed, everything is as expected. | bl.d @platform_get_irq <-- returns irq in r0 | | mov_s r2,r0 | brlt.d r2, 0, @.L112 | | st_s r0,[sp] <-- irq isaved is actual return value above | st r0,[r13,160] #arc_pmu.18_27->irq | | bl.d @__request_percpu_irq <-- r0 unchanged so actual irq returned | add r4,r4,r12 #, tmp363, __ptr Cc: <stable@vger.kernel.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch/arc/kernel')
-rw-r--r--arch/arc/kernel/perf_event.c27
1 files changed, 18 insertions, 9 deletions
diff --git a/arch/arc/kernel/perf_event.c b/arch/arc/kernel/perf_event.c
index 79849f37e782..145722f80c9b 100644
--- a/arch/arc/kernel/perf_event.c
+++ b/arch/arc/kernel/perf_event.c
@@ -562,7 +562,7 @@ static int arc_pmu_device_probe(struct platform_device *pdev)
{
struct arc_reg_pct_build pct_bcr;
struct arc_reg_cc_build cc_bcr;
- int i, has_interrupts, irq;
+ int i, has_interrupts, irq = -1;
int counter_size; /* in bits */
union cc_name {
@@ -637,19 +637,28 @@ static int arc_pmu_device_probe(struct platform_device *pdev)
.attr_groups = arc_pmu->attr_groups,
};
- if (has_interrupts && (irq = platform_get_irq(pdev, 0) >= 0)) {
+ if (has_interrupts) {
+ irq = platform_get_irq(pdev, 0);
+ if (irq >= 0) {
+ int ret;
- arc_pmu->irq = irq;
+ arc_pmu->irq = irq;
- /* intc map function ensures irq_set_percpu_devid() called */
- request_percpu_irq(irq, arc_pmu_intr, "ARC perf counters",
- this_cpu_ptr(&arc_pmu_cpu));
+ /* intc map function ensures irq_set_percpu_devid() called */
+ ret = request_percpu_irq(irq, arc_pmu_intr, "ARC perf counters",
+ this_cpu_ptr(&arc_pmu_cpu));
+
+ if (!ret)
+ on_each_cpu(arc_cpu_pmu_irq_init, &irq, 1);
+ else
+ irq = -1;
+ }
- on_each_cpu(arc_cpu_pmu_irq_init, &irq, 1);
- } else {
- arc_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
}
+ if (irq == -1)
+ arc_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
+
/*
* perf parser doesn't really like '-' symbol in events name, so let's
* use '_' in arc pct name as it goes to kernel PMU event prefix.