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powerpc/perf: Use guard(irqsave)() in eight functions

Message ID 096fc4ee-8ffe-4eb6-88f8-28dc944b079f@web.de (mailing list archive)
State New
Headers show
Series powerpc/perf: Use guard(irqsave)() in eight functions | expand

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Commit Message

Markus Elfring Sept. 16, 2024, 5:40 p.m. UTC 
From: Markus Elfring <elfring@users.sourceforge.net>
Date: Mon, 16 Sep 2024 19:25:00 +0200

Scope-based resource management became supported for some
programming interfaces by contributions of Peter Zijlstra on 2023-05-26.
See also the commit 54da6a0924311c7cf5015533991e44fb8eb12773 ("locking:
Introduce __cleanup() based infrastructure").

* Thus replace local_irq_save() and local_irq_restore() calls by calls
  of the macro “guard(irqsave)”.

* Omit the local variables “flags” and “irq_flags”.

* Replace selected usage of the label “out” by a few return statements.


This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 arch/powerpc/perf/core-book3s.c | 102 +++++++++++++-------------------
 1 file changed, 42 insertions(+), 60 deletions(-)

--
2.46.0

Comments

Michael Ellerman Sept. 20, 2024, 5:05 a.m. UTC | #1 
Markus Elfring <Markus.Elfring@web.de> writes:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Mon, 16 Sep 2024 19:25:00 +0200
>
> Scope-based resource management became supported for some
> programming interfaces by contributions of Peter Zijlstra on 2023-05-26.
> See also the commit 54da6a0924311c7cf5015533991e44fb8eb12773 ("locking:
> Introduce __cleanup() based infrastructure").
>
> * Thus replace local_irq_save() and local_irq_restore() calls by calls
>   of the macro “guard(irqsave)”.
>
> * Omit the local variables “flags” and “irq_flags”.
>
> * Replace selected usage of the label “out” by a few return statements.
>
>
> This issue was detected by using the Coccinelle software.
>
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
>  arch/powerpc/perf/core-book3s.c | 102 +++++++++++++-------------------
>  1 file changed, 42 insertions(+), 60 deletions(-)

These mostly look good.

I don't think the change to power_pmu_event_init() is an improvement.

I'll drop that hunk when applying, or you can send a v2 without that
change if you prefer.

cheers

> @@ -1996,7 +1980,7 @@ static bool is_event_blacklisted(u64 ev)
>  static int power_pmu_event_init(struct perf_event *event)
>  {
>  	u64 ev;
> -	unsigned long flags, irq_flags;
> +	unsigned long flags;
>  	struct perf_event *ctrs[MAX_HWEVENTS];
>  	u64 events[MAX_HWEVENTS];
>  	unsigned int cflags[MAX_HWEVENTS];
> @@ -2115,43 +2099,41 @@ static int power_pmu_event_init(struct perf_event *event)
>  	if (check_excludes(ctrs, cflags, n, 1))
>  		return -EINVAL;
>
> -	local_irq_save(irq_flags);
> -	cpuhw = this_cpu_ptr(&cpu_hw_events);
> +	{
> +		guard(irqsave)();
> +		cpuhw = this_cpu_ptr(&cpu_hw_events);
>
> -	err = power_check_constraints(cpuhw, events, cflags, n + 1, ctrs);
> +		err = power_check_constraints(cpuhw, events, cflags, n + 1, ctrs);
>
> -	if (has_branch_stack(event)) {
> -		u64 bhrb_filter = -1;
> +		if (has_branch_stack(event)) {
> +			u64 bhrb_filter = -1;
>
> -		/*
> -		 * Currently no PMU supports having multiple branch filters
> -		 * at the same time. Branch filters are set via MMCRA IFM[32:33]
> -		 * bits for Power8 and above. Return EOPNOTSUPP when multiple
> -		 * branch filters are requested in the event attr.
> -		 *
> -		 * When opening event via perf_event_open(), branch_sample_type
> -		 * gets adjusted in perf_copy_attr(). Kernel will automatically
> -		 * adjust the branch_sample_type based on the event modifier
> -		 * settings to include PERF_SAMPLE_BRANCH_PLM_ALL. Hence drop
> -		 * the check for PERF_SAMPLE_BRANCH_PLM_ALL.
> -		 */
> -		if (hweight64(event->attr.branch_sample_type & ~PERF_SAMPLE_BRANCH_PLM_ALL) > 1) {
> -			local_irq_restore(irq_flags);
> -			return -EOPNOTSUPP;
> -		}
> +			/*
> +			 * Currently no PMU supports having multiple branch filters
> +			 * at the same time. Branch filters are set via MMCRA IFM[32:33]
> +			 * bits for Power8 and above. Return EOPNOTSUPP when multiple
> +			 * branch filters are requested in the event attr.
> +			 *
> +			 * When opening event via perf_event_open(), branch_sample_type
> +			 * gets adjusted in perf_copy_attr(). Kernel will automatically
> +			 * adjust the branch_sample_type based on the event modifier
> +			 * settings to include PERF_SAMPLE_BRANCH_PLM_ALL. Hence drop
> +			 * the check for PERF_SAMPLE_BRANCH_PLM_ALL.
> +			 */
> +			if (hweight64(event->attr.branch_sample_type & ~PERF_SAMPLE_BRANCH_PLM_ALL)
> +			    > 1)
> +				return -EOPNOTSUPP;
>
> -		if (ppmu->bhrb_filter_map)
> -			bhrb_filter = ppmu->bhrb_filter_map(
> -					event->attr.branch_sample_type);
> +			if (ppmu->bhrb_filter_map)
> +				bhrb_filter = ppmu->bhrb_filter_map(event->attr.branch_sample_type);
>
> -		if (bhrb_filter == -1) {
> -			local_irq_restore(irq_flags);
> -			return -EOPNOTSUPP;
> +			if (bhrb_filter == -1)
> +				return -EOPNOTSUPP;
> +
> +			cpuhw->bhrb_filter = bhrb_filter;
>  		}
> -		cpuhw->bhrb_filter = bhrb_filter;
>  	}
>
> -	local_irq_restore(irq_flags);
>  	if (err)
>  		return -EINVAL;
>
> --
> 2.46.0
Markus Elfring Sept. 20, 2024, 6:52 a.m. UTC | #2 
>> Scope-based resource management became supported for some
>> programming interfaces by contributions of Peter Zijlstra on 2023-05-26.
>> See also the commit 54da6a0924311c7cf5015533991e44fb8eb12773 ("locking:
>> Introduce __cleanup() based infrastructure").
>>
>> * Thus replace local_irq_save() and local_irq_restore() calls by calls
>>   of the macro “guard(irqsave)”.
…
>> ---
>>  arch/powerpc/perf/core-book3s.c | 102 +++++++++++++-------------------
>>  1 file changed, 42 insertions(+), 60 deletions(-)
>
> These mostly look good.

Thanks for this positive feedback.


> I don't think the change to power_pmu_event_init() is an improvement.

I presented an other development opinion.


> I'll drop that hunk when applying,

I guess that there are further opportunities to clarify remaining change resistance.


> or you can send a v2 without that change if you prefer.

Not yet.

…
>> @@ -1996,7 +1980,7 @@ static bool is_event_blacklisted(u64 ev)
>>  static int power_pmu_event_init(struct perf_event *event)
>>  {
>>  	u64 ev;
>> -	unsigned long flags, irq_flags;
>> +	unsigned long flags;
>>  	struct perf_event *ctrs[MAX_HWEVENTS];
>>  	u64 events[MAX_HWEVENTS];
>>  	unsigned int cflags[MAX_HWEVENTS];
>> @@ -2115,43 +2099,41 @@ static int power_pmu_event_init(struct perf_event *event)
>>  	if (check_excludes(ctrs, cflags, n, 1))
>>  		return -EINVAL;
>>
>> -	local_irq_save(irq_flags);
>> -	cpuhw = this_cpu_ptr(&cpu_hw_events);
>> +	{
>> +		guard(irqsave)();
>> +		cpuhw = this_cpu_ptr(&cpu_hw_events);
>>
>> -	err = power_check_constraints(cpuhw, events, cflags, n + 1, ctrs);
>> +		err = power_check_constraints(cpuhw, events, cflags, n + 1, ctrs);
>>
>> -	if (has_branch_stack(event)) {
>> -		u64 bhrb_filter = -1;
>> +		if (has_branch_stack(event)) {
>> +			u64 bhrb_filter = -1;
>>
>> -		/*
>> -		 * Currently no PMU supports having multiple branch filters
>> -		 * at the same time. Branch filters are set via MMCRA IFM[32:33]
>> -		 * bits for Power8 and above. Return EOPNOTSUPP when multiple
>> -		 * branch filters are requested in the event attr.
>> -		 *
>> -		 * When opening event via perf_event_open(), branch_sample_type
>> -		 * gets adjusted in perf_copy_attr(). Kernel will automatically
>> -		 * adjust the branch_sample_type based on the event modifier
>> -		 * settings to include PERF_SAMPLE_BRANCH_PLM_ALL. Hence drop
>> -		 * the check for PERF_SAMPLE_BRANCH_PLM_ALL.
>> -		 */
>> -		if (hweight64(event->attr.branch_sample_type & ~PERF_SAMPLE_BRANCH_PLM_ALL) > 1) {
>> -			local_irq_restore(irq_flags);
>> -			return -EOPNOTSUPP;
>> -		}
>> +			/*
>> +			 * Currently no PMU supports having multiple branch filters
>> +			 * at the same time. Branch filters are set via MMCRA IFM[32:33]
>> +			 * bits for Power8 and above. Return EOPNOTSUPP when multiple
>> +			 * branch filters are requested in the event attr.
>> +			 *
>> +			 * When opening event via perf_event_open(), branch_sample_type
>> +			 * gets adjusted in perf_copy_attr(). Kernel will automatically
>> +			 * adjust the branch_sample_type based on the event modifier
>> +			 * settings to include PERF_SAMPLE_BRANCH_PLM_ALL. Hence drop
>> +			 * the check for PERF_SAMPLE_BRANCH_PLM_ALL.
>> +			 */
>> +			if (hweight64(event->attr.branch_sample_type & ~PERF_SAMPLE_BRANCH_PLM_ALL)
>> +			    > 1)
>> +				return -EOPNOTSUPP;
>>
>> -		if (ppmu->bhrb_filter_map)
>> -			bhrb_filter = ppmu->bhrb_filter_map(
>> -					event->attr.branch_sample_type);
>> +			if (ppmu->bhrb_filter_map)
>> +				bhrb_filter = ppmu->bhrb_filter_map(event->attr.branch_sample_type);
>>
>> -		if (bhrb_filter == -1) {
>> -			local_irq_restore(irq_flags);
>> -			return -EOPNOTSUPP;
>> +			if (bhrb_filter == -1)
>> +				return -EOPNOTSUPP;
>> +
>> +			cpuhw->bhrb_filter = bhrb_filter;
>>  		}
>> -		cpuhw->bhrb_filter = bhrb_filter;
>>  	}
>>
>> -	local_irq_restore(irq_flags);
>>  	if (err)
>>  		return -EINVAL;
>>
>> --
>> 2.46.0

* Under which circumstances would you find it acceptable to use
  the proposed compound statement?

* Would you eventually prefer to apply a macro like “scoped_guard” here?
  https://elixir.bootlin.com/linux/v6.11/source/include/linux/cleanup.h#L140


Regards,
Markus
diff mbox series

Patch

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 42867469752d..6416c629a2b1 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -895,7 +895,7 @@  static int any_pmc_overflown(struct cpu_hw_events *cpuhw)
 /* Called from sysrq_handle_showregs() */
 void perf_event_print_debug(void)
 {
-	unsigned long sdar, sier, flags;
+	unsigned long sdar, sier;
 	u32 pmcs[MAX_HWEVENTS];
 	int i;

@@ -907,7 +907,7 @@  void perf_event_print_debug(void)
 	if (!ppmu->n_counter)
 		return;

-	local_irq_save(flags);
+	guard(irqsave)();

 	pr_info("CPU: %d PMU registers, ppmu = %s n_counters = %d",
 		 smp_processor_id(), ppmu->name, ppmu->n_counter);
@@ -949,8 +949,6 @@  void perf_event_print_debug(void)
 #endif
 	pr_info("SIAR:  %016lx SDAR:  %016lx SIER:  %016lx\n",
 		mfspr(SPRN_SIAR), sdar, sier);
-
-	local_irq_restore(flags);
 }

 /*
@@ -1298,11 +1296,12 @@  static void write_mmcr0(struct cpu_hw_events *cpuhw, unsigned long mmcr0)
 static void power_pmu_disable(struct pmu *pmu)
 {
 	struct cpu_hw_events *cpuhw;
-	unsigned long flags, mmcr0, val, mmcra;
+	unsigned long mmcr0, val, mmcra;

 	if (!ppmu)
 		return;
-	local_irq_save(flags);
+
+	guard(irqsave)();
 	cpuhw = this_cpu_ptr(&cpu_hw_events);

 	if (!cpuhw->disabled) {
@@ -1398,8 +1397,6 @@  static void power_pmu_disable(struct pmu *pmu)
 		}
 #endif
 	}
-
-	local_irq_restore(flags);
 }

 /*
@@ -1411,7 +1408,6 @@  static void power_pmu_enable(struct pmu *pmu)
 {
 	struct perf_event *event;
 	struct cpu_hw_events *cpuhw;
-	unsigned long flags;
 	long i;
 	unsigned long val, mmcr0;
 	s64 left;
@@ -1422,15 +1418,16 @@  static void power_pmu_enable(struct pmu *pmu)

 	if (!ppmu)
 		return;
-	local_irq_save(flags);
+
+	guard(irqsave)();

 	cpuhw = this_cpu_ptr(&cpu_hw_events);
 	if (!cpuhw->disabled)
-		goto out;
+		return;

 	if (cpuhw->n_events == 0) {
 		ppc_set_pmu_inuse(0);
-		goto out;
+		return;
 	}

 	cpuhw->disabled = 0;
@@ -1474,7 +1471,7 @@  static void power_pmu_enable(struct pmu *pmu)
 			       &cpuhw->mmcr, cpuhw->event, ppmu->flags)) {
 		/* shouldn't ever get here */
 		printk(KERN_ERR "oops compute_mmcr failed\n");
-		goto out;
+		return;
 	}

 	if (!(ppmu->flags & PPMU_ARCH_207S)) {
@@ -1577,10 +1574,6 @@  static void power_pmu_enable(struct pmu *pmu)
 		mb();
 		mtspr(SPRN_MMCRA, cpuhw->mmcr.mmcra);
 	}
-
- out:
-
-	local_irq_restore(flags);
 }

 static int collect_events(struct perf_event *group, int max_count,
@@ -1619,11 +1612,10 @@  static int collect_events(struct perf_event *group, int max_count,
 static int power_pmu_add(struct perf_event *event, int ef_flags)
 {
 	struct cpu_hw_events *cpuhw;
-	unsigned long flags;
 	int n0;
 	int ret = -EAGAIN;

-	local_irq_save(flags);
+	guard(irqsave)();
 	perf_pmu_disable(event->pmu);

 	/*
@@ -1685,7 +1677,6 @@  static int power_pmu_add(struct perf_event *event, int ef_flags)
 	}

 	perf_pmu_enable(event->pmu);
-	local_irq_restore(flags);
 	return ret;
 }

@@ -1696,9 +1687,8 @@  static void power_pmu_del(struct perf_event *event, int ef_flags)
 {
 	struct cpu_hw_events *cpuhw;
 	long i;
-	unsigned long flags;

-	local_irq_save(flags);
+	guard(irqsave)();
 	perf_pmu_disable(event->pmu);

 	power_pmu_read(event);
@@ -1740,7 +1730,6 @@  static void power_pmu_del(struct perf_event *event, int ef_flags)
 		power_pmu_bhrb_disable(event);

 	perf_pmu_enable(event->pmu);
-	local_irq_restore(flags);
 }

 /*
@@ -1750,7 +1739,6 @@  static void power_pmu_del(struct perf_event *event, int ef_flags)

 static void power_pmu_start(struct perf_event *event, int ef_flags)
 {
-	unsigned long flags;
 	s64 left;
 	unsigned long val;

@@ -1763,7 +1751,7 @@  static void power_pmu_start(struct perf_event *event, int ef_flags)
 	if (ef_flags & PERF_EF_RELOAD)
 		WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));

-	local_irq_save(flags);
+	guard(irqsave)();
 	perf_pmu_disable(event->pmu);

 	event->hw.state = 0;
@@ -1777,20 +1765,17 @@  static void power_pmu_start(struct perf_event *event, int ef_flags)

 	perf_event_update_userpage(event);
 	perf_pmu_enable(event->pmu);
-	local_irq_restore(flags);
 }

 static void power_pmu_stop(struct perf_event *event, int ef_flags)
 {
-	unsigned long flags;
-
 	if (!event->hw.idx || !event->hw.sample_period)
 		return;

 	if (event->hw.state & PERF_HES_STOPPED)
 		return;

-	local_irq_save(flags);
+	guard(irqsave)();
 	perf_pmu_disable(event->pmu);

 	power_pmu_read(event);
@@ -1799,7 +1784,6 @@  static void power_pmu_stop(struct perf_event *event, int ef_flags)

 	perf_event_update_userpage(event);
 	perf_pmu_enable(event->pmu);
-	local_irq_restore(flags);
 }

 /*
@@ -1996,7 +1980,7 @@  static bool is_event_blacklisted(u64 ev)
 static int power_pmu_event_init(struct perf_event *event)
 {
 	u64 ev;
-	unsigned long flags, irq_flags;
+	unsigned long flags;
 	struct perf_event *ctrs[MAX_HWEVENTS];
 	u64 events[MAX_HWEVENTS];
 	unsigned int cflags[MAX_HWEVENTS];
@@ -2115,43 +2099,41 @@  static int power_pmu_event_init(struct perf_event *event)
 	if (check_excludes(ctrs, cflags, n, 1))
 		return -EINVAL;

-	local_irq_save(irq_flags);
-	cpuhw = this_cpu_ptr(&cpu_hw_events);
+	{
+		guard(irqsave)();
+		cpuhw = this_cpu_ptr(&cpu_hw_events);

-	err = power_check_constraints(cpuhw, events, cflags, n + 1, ctrs);
+		err = power_check_constraints(cpuhw, events, cflags, n + 1, ctrs);

-	if (has_branch_stack(event)) {
-		u64 bhrb_filter = -1;
+		if (has_branch_stack(event)) {
+			u64 bhrb_filter = -1;

-		/*
-		 * Currently no PMU supports having multiple branch filters
-		 * at the same time. Branch filters are set via MMCRA IFM[32:33]
-		 * bits for Power8 and above. Return EOPNOTSUPP when multiple
-		 * branch filters are requested in the event attr.
-		 *
-		 * When opening event via perf_event_open(), branch_sample_type
-		 * gets adjusted in perf_copy_attr(). Kernel will automatically
-		 * adjust the branch_sample_type based on the event modifier
-		 * settings to include PERF_SAMPLE_BRANCH_PLM_ALL. Hence drop
-		 * the check for PERF_SAMPLE_BRANCH_PLM_ALL.
-		 */
-		if (hweight64(event->attr.branch_sample_type & ~PERF_SAMPLE_BRANCH_PLM_ALL) > 1) {
-			local_irq_restore(irq_flags);
-			return -EOPNOTSUPP;
-		}
+			/*
+			 * Currently no PMU supports having multiple branch filters
+			 * at the same time. Branch filters are set via MMCRA IFM[32:33]
+			 * bits for Power8 and above. Return EOPNOTSUPP when multiple
+			 * branch filters are requested in the event attr.
+			 *
+			 * When opening event via perf_event_open(), branch_sample_type
+			 * gets adjusted in perf_copy_attr(). Kernel will automatically
+			 * adjust the branch_sample_type based on the event modifier
+			 * settings to include PERF_SAMPLE_BRANCH_PLM_ALL. Hence drop
+			 * the check for PERF_SAMPLE_BRANCH_PLM_ALL.
+			 */
+			if (hweight64(event->attr.branch_sample_type & ~PERF_SAMPLE_BRANCH_PLM_ALL)
+			    > 1)
+				return -EOPNOTSUPP;

-		if (ppmu->bhrb_filter_map)
-			bhrb_filter = ppmu->bhrb_filter_map(
-					event->attr.branch_sample_type);
+			if (ppmu->bhrb_filter_map)
+				bhrb_filter = ppmu->bhrb_filter_map(event->attr.branch_sample_type);

-		if (bhrb_filter == -1) {
-			local_irq_restore(irq_flags);
-			return -EOPNOTSUPP;
+			if (bhrb_filter == -1)
+				return -EOPNOTSUPP;
+
+			cpuhw->bhrb_filter = bhrb_filter;
 		}
-		cpuhw->bhrb_filter = bhrb_filter;
 	}

-	local_irq_restore(irq_flags);
 	if (err)
 		return -EINVAL;