From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 918373E92A5; Tue, 10 Mar 2026 20:10:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773173427; cv=none; b=BBt3eet9bO358TeW8jcwFhD9mwZHDI+wF0VR430r12UBipscwpoOWDQRiaa8zBe9Jop9L3DuqQvVxgtK6w+Wn99dzH8anyXoeG7EY9Q12ROn5OqWaQSOXw3GjV2rvQTxwZiF/9hMX+n5MxzN2I4W5986yeGM3+12LhtbtxvtQAA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773173427; c=relaxed/simple; bh=XfA5H3AsxhCs2jUx2EWo2pLzbnzAQC+9ctmRamPslRM=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=YMNs54x7q/YxidYFcwOffwfQglUrxW2L/4nvpiQscK9Moc/HY72mXu9YnuxQQTgRqmV9SAGL7VOydBQNwoHwsfiT2DnwiA/52twCdRP20+jNjubcgSddy2C9R6jzelLuwdwVPPgoBOthE9SyQENBlAVAoXS4X4bnd4WG9OtDgrE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ivFo7AVu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ivFo7AVu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E011C19423; Tue, 10 Mar 2026 20:10:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773173427; bh=XfA5H3AsxhCs2jUx2EWo2pLzbnzAQC+9ctmRamPslRM=; h=Date:From:To:Cc:Subject:References:From; b=ivFo7AVuHlM3ewrftnCH9GP+N0KGc7DPl9pBUivAsyi7aSw1ofLl7YXSikDo3uueR OHd4+uM4NUBLx63ESalk79vBcgOjVQhHBHJxCKtmawe+L6m3LmQKrIVFYIz3KuIEpd AhvZKNxHpZv31q4UsYAzWONh4zhQ8KQBeM5gpO9MErXehzdnX/xyHYxwFUwgOEtGtL c2jFligw3z8pvDziTcXjosVDQSm489kUhjix852eQz5Po79bXAidYcFnfOUFvzJ7ro 25rjvKElKw+xWrb5v7pqXbI/HKPL4VMB3eZbk324JtHegTJtJczvnoUcZDjw7SZpqi XuWBoe3bSGSxw== Received: from rostedt by gandalf with local (Exim 4.99.1) (envelope-from ) id 1w03PZ-00000002krt-06Cg; Tue, 10 Mar 2026 16:10:37 -0400 Message-ID: <20260310201036.879130564@kernel.org> User-Agent: quilt/0.69 Date: Tue, 10 Mar 2026 16:09:57 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Brian Geffon , John Stultz , Ian Rogers , Suleiman Souhlal Subject: [PATCH v2 3/3] tracing: Show TID and flags for PI futex system call trace event References: <20260310200954.285663884@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: Steven Rostedt 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) --- Changes since v1: https://lore.kernel.org/all/20260303174442.548b6524@gandalf.local.home/ - Updated to have the print processing in kernel/futex/syscall.c kernel/futex/syscalls.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index a46706d6bc6c..24d912d9b20d 100644 --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -211,6 +211,9 @@ void futex_print_syscall(struct seq_buf *s, int nr_args, unsigned long *args, unsigned int op, cmd; bool done = false; + op = args[1]; + cmd = op & FUTEX_CMD_MASK; + for (int i = 0; !done && i < nr_args; i++) { if (seq_buf_has_overflowed(s)) @@ -225,11 +228,30 @@ void futex_print_syscall(struct seq_buf *s, int nr_args, unsigned long *args, seq_buf_printf(s, " (%u)", val); else seq_buf_printf(s, " (0x%x)", val); + + switch(cmd) { + case FUTEX_LOCK_PI: + case FUTEX_UNLOCK_PI: + seq_buf_printf(s, " tid: %d", + val & FUTEX_TID_MASK); + + if (!(val & (FUTEX_OWNER_DIED|FUTEX_WAITERS))) + break; + + seq_buf_puts(s, " ("); + if (val & FUTEX_WAITERS) + seq_buf_puts(s, "WAITERS"); + if (val & FUTEX_OWNER_DIED) { + if (op & FUTEX_WAITERS) + seq_buf_putc(s, '|'); + seq_buf_puts(s, "DIED"); + } + seq_buf_putc(s, ')'); + break; + } } continue; case 1: - op = args[i]; - cmd = op & FUTEX_CMD_MASK; if (cmd <= FUTEX_LOCK_PI2) seq_buf_printf(s, ", %s", __futex_cmds[cmd]); else -- 2.51.0