From abaf1e0355abb050f9c11d2d13a513caec80f7ad Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Thu, 17 Aug 2023 09:11:21 -0300 Subject: [PATCH] perf lock: Don't pass an ERR_PTR() directly to perf_session__delete() While debugging a segfault on 'perf lock contention' without an available perf.data file I noticed that it was basically calling: perf_session__delete(ERR_PTR(-1)) Resulting in: (gdb) run lock contention Starting program: /root/bin/perf lock contention [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib64/libthread_db.so.1". failed to open perf.data: No such file or directory (try 'perf record' first) Initializing perf session failed Program received signal SIGSEGV, Segmentation fault. 0x00000000005e7515 in auxtrace__free (session=0xffffffffffffffff) at util/auxtrace.c:2858 2858 if (!session->auxtrace) (gdb) p session $1 = (struct perf_session *) 0xffffffffffffffff (gdb) bt #0 0x00000000005e7515 in auxtrace__free (session=0xffffffffffffffff) at util/auxtrace.c:2858 #1 0x000000000057bb4d in perf_session__delete (session=0xffffffffffffffff) at util/session.c:300 #2 0x000000000047c421 in __cmd_contention (argc=0, argv=0x7fffffffe200) at builtin-lock.c:2161 #3 0x000000000047dc95 in cmd_lock (argc=0, argv=0x7fffffffe200) at builtin-lock.c:2604 #4 0x0000000000501466 in run_builtin (p=0xe597a8 , argc=2, argv=0x7fffffffe200) at perf.c:322 #5 0x00000000005016d5 in handle_internal_command (argc=2, argv=0x7fffffffe200) at perf.c:375 #6 0x0000000000501824 in run_argv (argcp=0x7fffffffe02c, argv=0x7fffffffe020) at perf.c:419 #7 0x0000000000501b11 in main (argc=2, argv=0x7fffffffe200) at perf.c:535 (gdb) So just set it to NULL after using PTR_ERR(session) to decode the error as perf_session__delete(NULL) is supported. Fixes: eef4fee5e52071d5 ("perf lock: Dynamically allocate lockhash_table") Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Andi Kleen Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: K Prateek Nayak Cc: Kan Liang Cc: Leo Yan Cc: Mamatha Inamdar Cc: Mark Rutland Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Ross Zwisler Cc: Sean Christopherson Cc: Steven Rostedt (VMware) Cc: Tiezhu Yang Cc: Yang Jihong Link: https://lore.kernel.org/lkml/ZN4R1AYfsD2J8lRs@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-lock.c | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c index c15386cb103318..0cf1c5a2e03233 100644 --- a/tools/perf/builtin-lock.c +++ b/tools/perf/builtin-lock.c @@ -2052,6 +2052,7 @@ static int __cmd_contention(int argc, const char **argv) if (IS_ERR(session)) { pr_err("Initializing perf session failed\n"); err = PTR_ERR(session); + session = NULL; goto out_delete; }