drivers/perf: Prevent forced unbinding of PMU drivers

Forcefully unbinding PMU drivers during perf sampling will lead to
a kernel panic, because the perf upper-layer framework call a NULL
pointer in this situation.

To solve this issue, "suppress_bind_attrs" should be set to true, so
that bind/unbind can be disabled via sysfs and prevent unbinding PMU
drivers during perf sampling.

Signed-off-by: Qi Liu <liuqi115@huawei.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Link: https://lore.kernel.org/r/1594975763-32966-1-git-send-email-liuqi115@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>

drivers/perf/arm-ccn.c

@@ -1545,6 +1545,7 @@ static struct platform_driver arm_ccn_driver = {
 	.driver = {
 		.name = "arm-ccn",
 		.of_match_table = arm_ccn_match,
+		.suppress_bind_attrs = true,
 	},
 	.probe = arm_ccn_probe,
 	.remove = arm_ccn_remove,