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 CBE3C11C83 for ; Mon, 28 Aug 2023 10:19:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F67FC433C7; Mon, 28 Aug 2023 10:19:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1693217952; bh=tW0RA2Di4G+ycEI3ZX5gI6Igc+l/32bZysRDIafBhQA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oBfiwOvUX6WVzZ2Cm33Qw7/1hrWLvtaf4fWpIh9XHhZVXLng7BFmGMS2NFl6undiG IJ9YMhI2sHnFAN8KVG0fPwI7XsxjjkAdkce01oO2Mnjr0X6unZTmguGHS356cEH3zl 64pD/OC1KMig9W8bMnceU/yv7Fno5A1lHR0FO2wg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Masami Hiramatsu , Sven Schnelle , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 6.4 013/129] tracing/synthetic: Skip first entry for stack traces Date: Mon, 28 Aug 2023 12:11:32 +0200 Message-ID: <20230828101157.829705569@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230828101157.383363777@linuxfoundation.org> References: <20230828101157.383363777@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sven Schnelle [ Upstream commit 887f92e09ef34a949745ad26ce82be69e2dabcf6 ] While debugging another issue I noticed that the stack trace output contains the number of entries on top: -0 [000] d..4. 203.322502: wake_lat: pid=0 delta=2268270616 stack=STACK: => 0x10 => __schedule+0xac6/0x1a98 => schedule+0x126/0x2c0 => schedule_timeout+0x242/0x2c0 => __wait_for_common+0x434/0x680 => __wait_rcu_gp+0x198/0x3e0 => synchronize_rcu+0x112/0x138 => ring_buffer_reset_online_cpus+0x140/0x2e0 => tracing_reset_online_cpus+0x15c/0x1d0 => tracing_set_clock+0x180/0x1d8 => hist_register_trigger+0x486/0x670 => event_hist_trigger_parse+0x494/0x1318 => trigger_process_regex+0x1d4/0x258 => event_trigger_write+0xb4/0x170 => vfs_write+0x210/0xad0 => ksys_write+0x122/0x208 Fix this by skipping the first element. Also replace the pointer logic with an index variable which is easier to read. Link: https://lkml.kernel.org/r/20230816154928.4171614-3-svens@linux.ibm.com Cc: Masami Hiramatsu Fixes: 00cf3d672a9d ("tracing: Allow synthetic events to pass around stacktraces") Signed-off-by: Sven Schnelle Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- kernel/trace/trace_events_synth.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-) diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c index da0627fa91caf..a4c58a932dfa6 100644 --- a/kernel/trace/trace_events_synth.c +++ b/kernel/trace/trace_events_synth.c @@ -350,7 +350,7 @@ static enum print_line_t print_synth_event(struct trace_iterator *iter, struct trace_seq *s = &iter->seq; struct synth_trace_event *entry; struct synth_event *se; - unsigned int i, n_u64; + unsigned int i, j, n_u64; char print_fmt[32]; const char *fmt; @@ -389,18 +389,13 @@ static enum print_line_t print_synth_event(struct trace_iterator *iter, n_u64 += STR_VAR_LEN_MAX / sizeof(u64); } } else if (se->fields[i]->is_stack) { - unsigned long *p, *end; union trace_synth_field *data = &entry->fields[n_u64]; - - p = (void *)entry + data->as_dynamic.offset; - end = (void *)p + data->as_dynamic.len - (sizeof(long) - 1); + unsigned long *p = (void *)entry + data->as_dynamic.offset; trace_seq_printf(s, "%s=STACK:\n", se->fields[i]->name); - - for (; *p && p < end; p++) - trace_seq_printf(s, "=> %pS\n", (void *)*p); + for (j = 1; j < data->as_dynamic.len / sizeof(long); j++) + trace_seq_printf(s, "=> %pS\n", (void *)p[j]); n_u64++; - } else { struct trace_print_flags __flags[] = { __def_gfpflag_names, {-1, NULL} }; @@ -490,10 +485,6 @@ static unsigned int trace_stack(struct synth_trace_event *entry, break; } - /* Include the zero'd element if it fits */ - if (len < HIST_STACKTRACE_DEPTH) - len++; - len *= sizeof(long); /* Find the dynamic section to copy the stack into. */ -- 2.40.1