[PATCH] perf/x86: Fix missing error code in init_hw_perf_events()

[PATCH] perf/x86: Fix missing error code in init_hw_perf_events()

[Bramwel Barack]

In init_hw_perf_events(), a fallback block intentionally clears the
'err' variable to 0 when a vendor PMU driver is missing, allowing the
kernel to fall back to software events safely.

However, further down the initialization path, a second hardware safety
validation check is performed via check_hw_exists(). If this hardware check
fails, the execution control paths jump straight to the 'out_bad_pmu'
cleanup label. Because 'err' was cleared or initialized to 0 earlier, the
function erroneously returns 0 (Success) to the initialization manager,
despite wiping out the PMU configuration structures via memset.

Fix this by explicitly assigning -ENODEV to 'err' before jumping to the
cleanup sequence when check_hw_exists() fails.

Signed-off-by: Bramwel Barack  <bramwelbarack89@gmail.com>
---
 arch/x86/events/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index d1af33d96d0a..81873eda5b17 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2164,9 +2164,10 @@ static int __init init_hw_perf_events(void)
 	pmu_check_apic();
 
 	/* sanity check that the hardware exists or is emulated */
-	if (!check_hw_exists(&pmu, x86_pmu.cntr_mask, x86_pmu.fixed_cntr_mask))
+	if (!check_hw_exists(&pmu, x86_pmu.cntr_mask, x86_pmu.fixed_cntr_mask)) {
+		err = -ENODEV;
 		goto out_bad_pmu;
-
+	}
 	pr_cont("%s PMU driver.\n", x86_pmu.name);
 
 	/* enable userspace RDPMC usage by default */
-- 
2.55.0