s390/cpum_cf: Corrected return code for unauthorized counter sets

Previously, the cpum_cf PMU returned -EPERM if a counter is requested and
the counter set to which the counter belongs is not authorized.  According
to the perf_event_open() system call manual, an error code of EPERM indicates
an unsupported exclude setting or CAP_SYS_ADMIN is missing.

Use ENOENT to indicate that particular counters are not available when the
counter set which contains the counter is not authorized.  For generic events,
this might trigger a fall back, for example, to a software event.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
index 56fdad4..a956340 100644 (file)
--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -157,10 +157,14 @@ static int validate_ctr_auth(const struct hw_perf_event *hwc)
 
        cpuhw = &get_cpu_var(cpu_hw_events);
 
-       /* check authorization for cpu counter sets */
+       /* Check authorization for cpu counter sets.
+        * If the particular CPU counter set is not authorized,
+        * return with -ENOENT in order to fall back to other
+        * PMUs that might suffice the event request.
+        */
        ctrs_state = cpumf_state_ctl[hwc->config_base];
        if (!(ctrs_state & cpuhw->info.auth_ctl))
-               err = -EPERM;
+               err = -ENOENT;
 
        put_cpu_var(cpu_hw_events);
        return err;
@@ -536,7 +540,7 @@ static int cpumf_pmu_add(struct perf_event *event, int flags)
         */
        if (!(cpuhw->flags & PERF_EVENT_TXN))
                if (validate_ctr_auth(&event->hw))
-                       return -EPERM;
+                       return -ENOENT;
 
        ctr_set_enable(&cpuhw->state, event->hw.config_base);
        event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
@@ -611,7 +615,7 @@ static int cpumf_pmu_commit_txn(struct pmu *pmu)
        state = cpuhw->state & ~((1 << CPUMF_LCCTL_ENABLE_SHIFT) - 1);
        state >>= CPUMF_LCCTL_ENABLE_SHIFT;
        if ((state & cpuhw->info.auth_ctl) != state)
-               return -EPERM;
+               return -ENOENT;
 
        cpuhw->flags &= ~PERF_EVENT_TXN;
        perf_pmu_enable(pmu);