[PATCH-REBASED,2/2] perf/core: change errno for sampling event not supported in hardware
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Message ID 1464607906-16012-3-git-send-email-vgupta@synopsys.com
State New
Headers show

Commit Message

Vineet Gupta May 30, 2016, 11:31 a.m. UTC
This allows userspace to identify this case specifically from the
catch all error msg it prints currently.

This is an ABI change

Before
-------
| # perf record ls
| Error:
| The sys_perf_event_open() syscall returned with 524 (Unknown error 524)
| for event (cycles:ppp).
| /bin/dmesg may provide additional information.
| No CONFIG_PERF_EVENTS=y kernel support configured?

Now
-------
| # perf record ls
| Error:
| PMU Hardware doesn't support sampling/overflow-interrupts.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch
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diff --git a/kernel/events/core.c b/kernel/events/core.c
index 274450efea90..a156ec0cb420 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9271,7 +9271,7 @@  SYSCALL_DEFINE5(perf_event_open,
 
 	if (is_sampling_event(event)) {
 		if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) {
-			err = -ENOTSUPP;
+			err = -EOPNOTSUPP;
 			goto err_alloc;
 		}
 	}