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| author | Vineet Gupta <vgupta@synopsys.com> | 2020-10-22 13:16:22 +0300 |
|---|---|---|
| committer | Vineet Gupta <vgupta@synopsys.com> | 2020-10-22 20:57:58 +0300 |
| commit | 8c42a5c02bec6c7eccf08957be3c6c8fccf9790b (patch) | |
| tree | baaec812df674806c3e7e1f6ce5e3e4534a5b997 | |
| parent | 6364d1b41cc382db3b03cf33c57b6007ee8f09cf (diff) | |
| download | linux-8c42a5c02bec6c7eccf08957be3c6c8fccf9790b.tar.xz | |
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>
| -rw-r--r-- | arch/arc/kernel/perf_event.c | 27 |
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. |