perf: Ensure bpf_perf_link path is properly serialized

perf: Ensure bpf_perf_link path is properly serialized

[ Upstream commit 7ed9138a72829d2035ecbd8dbd35b1bc3c137c40 ]

Ravi reported that the bpf_perf_link_attach() usage of
perf_event_set_bpf_prog() is not serialized by ctx->mutex, unlike the
PERF_EVENT_IOC_SET_BPF case.

Reported-by: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Link: https://lkml.kernel.org/r/20250307193305.486326750@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>