From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Brian Geffon <bgeffon@google.com>,
John Stultz <jstultz@google.com>, Ian Rogers <irogers@google.com>,
Suleiman Souhlal <suleiman@google.com>
Subject: [PATCH 3/2] tracing: Show TID and flags for PI futex system call trace event
Date: Tue, 3 Mar 2026 17:44:42 -0500 [thread overview]
Message-ID: <20260303174442.548b6524@gandalf.local.home> (raw)
In-Reply-To: <20260303214735.002154462@kernel.org>
From: Steven Rostedt <rostedt@goodmis.org>
For the futex system call trace event for FUTEX_LOCK_PI and
FUTEX_UNLOCK_PI commands, show the TID from the value (which is usually in
hex) as well as translate the flags (DIED and WAITERS).
pi_mutex_hammer-1098 [000] ..... 121.876928: sys_futex(uaddr: 0x560f40cc8180 (0x450) tid: 1104, FUTEX_LOCK_PI|FUTEX_PRIVATE_FLAG, val: 0, timespec: 0x7f2f9d4b1e50 (0.000100000))
pi_mutex_hammer-1128 [000] ..... 121.877120: sys_futex(uaddr: 0x560f40cc8180 (0x8000042a) tid: 1066 (WAITERS), FUTEX_LOCK_PI|FUTEX_PRIVATE_FLAG, val: 0, timespec: 0x7f2f8e493e50 (0.000100000))
pi_mutex_hammer-1106 [000] ..... 121.877242: sys_futex(uaddr: 0x560f40cc8180 (0x80000452) tid: 1106 (WAITERS), FUTEX_UNLOCK_PI|FUTEX_PRIVATE_FLAG, val: 0)
This makes it easier to see the hand off of a mutex and who the owner was.
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace_syscalls.c | 25 +++++++++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index d128dcb218a7..b3eddfee1a6b 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -300,6 +300,9 @@ sys_enter_futex_print(struct syscall_trace_enter *trace, struct syscall_metadata
trace_seq_printf(s, "%s(", entry->name);
+ op = trace->args[1];
+ cmd = op & FUTEX_CMD_MASK;
+
for (i = 0; !done && i < entry->nb_args; i++) {
if (trace_seq_has_overflowed(s))
@@ -314,11 +317,29 @@ sys_enter_futex_print(struct syscall_trace_enter *trace, struct syscall_metadata
trace_seq_printf(s, " (%u)", val);
else
trace_seq_printf(s, " (0x%x)", val);
+
+ switch(cmd) {
+ case FUTEX_LOCK_PI:
+ case FUTEX_UNLOCK_PI:
+ trace_seq_printf(s, " tid: %d", val & FUTEX_TID_MASK);
+
+ if (!(val & (FUTEX_OWNER_DIED|FUTEX_WAITERS)))
+ break;
+
+ trace_seq_puts(s, " (");
+ if (val & FUTEX_WAITERS)
+ trace_seq_puts(s, "WAITERS");
+ if (val & FUTEX_OWNER_DIED) {
+ if (op & FUTEX_WAITERS)
+ trace_seq_putc(s, '|');
+ trace_seq_puts(s, "DIED");
+ }
+ trace_seq_putc(s, ')');
+ break;
+ }
}
continue;
case 1:
- op = trace->args[i];
- cmd = op & FUTEX_CMD_MASK;
if (cmd <= FUTEX_LOCK_PI2)
trace_seq_printf(s, ", %s", __futex_cmds[cmd]);
else
--
2.51.0
prev parent reply other threads:[~2026-03-03 22:44 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-03 21:47 [PATCH 0/2] tracing: Read user data from futex system call trace event Steven Rostedt
2026-03-03 21:47 ` [PATCH 1/2] tracing: Have futex syscall trace event show specific user data Steven Rostedt
2026-03-04 9:07 ` Peter Zijlstra
2026-03-05 1:37 ` Steven Rostedt
2026-03-03 21:47 ` [PATCH 2/2] tracing: Update futex syscall trace event to show more commands Steven Rostedt
2026-03-03 22:44 ` Steven Rostedt [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260303174442.548b6524@gandalf.local.home \
--to=rostedt@goodmis.org \
--cc=akpm@linux-foundation.org \
--cc=bgeffon@google.com \
--cc=irogers@google.com \
--cc=jstultz@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mathieu.desnoyers@efficios.com \
--cc=mhiramat@kernel.org \
--cc=peterz@infradead.org \
--cc=suleiman@google.com \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox