[PATCH] perf/x86/rapl: Fix the error checking order

[PATCH] perf/x86/rapl: Fix the error checking order

[Dhananjay Ugwekar]

After the commit b4943b8bfc41 ("perf/x86/rapl: Add core energy counter
support for AMD CPUs"), the default "perf record"/"perf top" command is
broken in systems where there isn't a PMU registered for type
PERF_TYPE_RAW.

This is due to the change in order of error checks in rapl_pmu_event_init()
Due to which we return -EINVAL instead of -ENOENT, when we reach here from
the fallback loop in perf_init_event().

Move the "PMU and event type match" back to the beginning of the function
so that we return -ENOENT early on.

Reported-by: Koichiro Den <koichiro.den@canonical.com>
Closes: https://lore.kernel.org/all/uv7mz6vew2bzgre5jdpmwldxljp5djzmuiksqdcdwipfm4zm7w@ribobcretidk/
Fixes: b4943b8bfc41 ("perf/x86/rapl: Add core energy counter support for AMD CPUs")
Signed-off-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
---
 arch/x86/events/rapl.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/x86/events/rapl.c b/arch/x86/events/rapl.c
index d3bb3865c1b1..4952faf03e82 100644
--- a/arch/x86/events/rapl.c
+++ b/arch/x86/events/rapl.c
@@ -370,6 +370,10 @@ static int rapl_pmu_event_init(struct perf_event *event)
 	unsigned int rapl_pmu_idx;
 	struct rapl_pmus *rapl_pmus;
 
+	/* only look at RAPL events */
+	if (event->attr.type != event->pmu->type)
+		return -ENOENT;
+
 	/* unsupported modes and filters */
 	if (event->attr.sample_period) /* no sampling */
 		return -EINVAL;
@@ -387,10 +391,6 @@ static int rapl_pmu_event_init(struct perf_event *event)
 	rapl_pmus_scope = rapl_pmus->pmu.scope;
 
 	if (rapl_pmus_scope == PERF_PMU_SCOPE_PKG || rapl_pmus_scope == PERF_PMU_SCOPE_DIE) {
-		/* only look at RAPL package events */
-		if (event->attr.type != rapl_pmus_pkg->pmu.type)
-			return -ENOENT;
-
 		cfg = array_index_nospec((long)cfg, NR_RAPL_PKG_DOMAINS + 1);
 		if (!cfg || cfg >= NR_RAPL_PKG_DOMAINS + 1)
 			return -EINVAL;
@@ -398,10 +398,6 @@ static int rapl_pmu_event_init(struct perf_event *event)
 		bit = cfg - 1;
 		event->hw.event_base = rapl_model->rapl_pkg_msrs[bit].msr;
 	} else if (rapl_pmus_scope == PERF_PMU_SCOPE_CORE) {
-		/* only look at RAPL core events */
-		if (event->attr.type != rapl_pmus_core->pmu.type)
-			return -ENOENT;
-
 		cfg = array_index_nospec((long)cfg, NR_RAPL_CORE_DOMAINS + 1);
 		if (!cfg || cfg >= NR_RAPL_PKG_DOMAINS + 1)
 			return -EINVAL;
-- 
2.34.1

[tip: perf/urgent] perf/x86/rapl: Fix the error checking order

[tip-bot2 for Dhananjay Ugwekar]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     469c76a83bb9f6b2c7b2989c46617c4fe01fee79
Gitweb:        https://git.kernel.org/tip/469c76a83bb9f6b2c7b2989c46617c4fe01fee79
Author:        Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
AuthorDate:    Wed, 29 Jan 2025 08:05:14 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Sat, 08 Feb 2025 15:47:25 +01:00

perf/x86/rapl: Fix the error checking order

After the commit b4943b8bfc41 ("perf/x86/rapl: Add core energy counter
support for AMD CPUs"), the default "perf record"/"perf top" command is
broken in systems where there isn't a PMU registered for type
PERF_TYPE_RAW.

This is due to the change in order of error checks in rapl_pmu_event_init()
Due to which we return -EINVAL instead of -ENOENT, when we reach here from
the fallback loop in perf_init_event().

Move the "PMU and event type match" back to the beginning of the function
so that we return -ENOENT early on.

Closes: https://lore.kernel.org/all/uv7mz6vew2bzgre5jdpmwldxljp5djzmuiksqdcdwipfm4zm7w@ribobcretidk/
Fixes: b4943b8bfc41 ("perf/x86/rapl: Add core energy counter support for AMD CPUs")
Reported-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250129080513.30353-1-dhananjay.ugwekar@amd.com
---
 arch/x86/events/rapl.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/x86/events/rapl.c b/arch/x86/events/rapl.c
index d3bb386..4952faf 100644
--- a/arch/x86/events/rapl.c
+++ b/arch/x86/events/rapl.c
@@ -370,6 +370,10 @@ static int rapl_pmu_event_init(struct perf_event *event)
 	unsigned int rapl_pmu_idx;
 	struct rapl_pmus *rapl_pmus;
 
+	/* only look at RAPL events */
+	if (event->attr.type != event->pmu->type)
+		return -ENOENT;
+
 	/* unsupported modes and filters */
 	if (event->attr.sample_period) /* no sampling */
 		return -EINVAL;
@@ -387,10 +391,6 @@ static int rapl_pmu_event_init(struct perf_event *event)
 	rapl_pmus_scope = rapl_pmus->pmu.scope;
 
 	if (rapl_pmus_scope == PERF_PMU_SCOPE_PKG || rapl_pmus_scope == PERF_PMU_SCOPE_DIE) {
-		/* only look at RAPL package events */
-		if (event->attr.type != rapl_pmus_pkg->pmu.type)
-			return -ENOENT;
-
 		cfg = array_index_nospec((long)cfg, NR_RAPL_PKG_DOMAINS + 1);
 		if (!cfg || cfg >= NR_RAPL_PKG_DOMAINS + 1)
 			return -EINVAL;
@@ -398,10 +398,6 @@ static int rapl_pmu_event_init(struct perf_event *event)
 		bit = cfg - 1;
 		event->hw.event_base = rapl_model->rapl_pkg_msrs[bit].msr;
 	} else if (rapl_pmus_scope == PERF_PMU_SCOPE_CORE) {
-		/* only look at RAPL core events */
-		if (event->attr.type != rapl_pmus_core->pmu.type)
-			return -ENOENT;
-
 		cfg = array_index_nospec((long)cfg, NR_RAPL_CORE_DOMAINS + 1);
 		if (!cfg || cfg >= NR_RAPL_PKG_DOMAINS + 1)
 			return -EINVAL;