[PATCH] alpha/perf: Clean up stale comments referencing old hw_perf_* APIs

[Yunbo Lyu]

Two outdated comments in arch/alpha/kernel/perf_event.c referred to
functions from the deprecated hw_perf_* APIs that were removed more
than a decade ago:

1. hw_perf_disable():
   This was superseded by per-PMU disable APIs such as
   alpha_pmu_disable(), after commit 33696fc0d141 ("perf: Per PMU
   disable"). The comment has been updated to reflect the correct
   function name.

2. hw_perf_group_sched_in():
   This function was removed in commit a13c3afd9b62 ("perf, sparc:
   Implement group scheduling transactional APIs"). The corresponding
   comment mentioning it has been removed. The if (n_ev == 0) check in
   alpha_check_constraints() has also been removed, as this condition is
   never true. The alpha_check_constraints() function is only called
   from two places:

   - alpha_pmu_add(), which calls alpha_check_constraints() with
     n0 + 1, where n0 is the number of existing events (>= 0).
   - __hw_perf_event_init(), which calls it with n + 1, where n is the
     number of events in the group (>= 0).

   In both cases, the n_ev argument is guaranteed to be at least 1.
   Therefore, the check is redundant.

No functional changes; comments and dead code cleanup.

Fixes: 33696fc0d141 ("perf: Per PMU disable")
Fixes: a13c3afd9b62 ("perf, sparc: Implement group scheduling transactional APIs")

Signed-off-by: Yunbo Lyu <yunbolyu@xxxxxxxxxx>
---
 arch/alpha/kernel/perf_event.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/arch/alpha/kernel/perf_event.c b/arch/alpha/kernel/perf_event.c
index a3eaab094ece..2f57626ffcfb 100644
--- a/arch/alpha/kernel/perf_event.c
+++ b/arch/alpha/kernel/perf_event.c
@@ -35,7 +35,7 @@ struct cpu_hw_events {
 	int			enabled;
 	/* Number of events scheduled; also number entries valid in arrays below. */
 	int			n_events;
-	/* Number events added since last hw_perf_disable(). */
+	/* Number of events added since last alpha_pmu_disable(). */
 	int			n_added;
 	/* Events currently scheduled. */
 	struct perf_event	*event[MAX_HWEVENTS];
@@ -372,10 +372,6 @@ static int alpha_check_constraints(struct perf_event **events,
 				   unsigned long *evtypes, int n_ev)
 {
 
-	/* No HW events is possible from hw_perf_group_sched_in(). */
-	if (n_ev == 0)
-		return 0;
-
 	if (n_ev > alpha_pmu->num_pmcs)
 		return -1;
 
-- 
2.25.1