From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
stable@vger.kernel.org, "J. Avila" <elavila@google.com>,
Daniel Mentz <danielmentz@google.com>,
Will McVicker <willmcvicker@google.com>
Subject: [for-linus][PATCH 05/12] ring-buffer: Update write stamp with the correct ts
Date: Tue, 01 Dec 2020 10:58:40 -0500 [thread overview]
Message-ID: <20201201160005.780999537@goodmis.org> (raw)
In-Reply-To: 20201201155835.647858317@goodmis.org
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
The write stamp, used to calculate deltas between events, was updated with
the stale "ts" value in the "info" structure, and not with the updated "ts"
variable. This caused the deltas between events to be inaccurate, and when
crossing into a new sub buffer, had time go backwards.
Link: https://lkml.kernel.org/r/20201124223917.795844-1-elavila@google.com
Cc: stable@vger.kernel.org
Fixes: a389d86f7fd09 ("ring-buffer: Have nested events still record running time stamp")
Reported-by: "J. Avila" <elavila@google.com>
Tested-by: Daniel Mentz <danielmentz@google.com>
Tested-by: Will McVicker <willmcvicker@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/ring_buffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index dc83b3fa9fe7..bccaf88d3706 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3291,7 +3291,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
/* Nothing came after this event between C and E */
info->delta = ts - info->after;
(void)rb_time_cmpxchg(&cpu_buffer->write_stamp,
- info->after, info->ts);
+ info->after, ts);
info->ts = ts;
} else {
/*
--
2.28.0
next prev parent reply other threads:[~2020-12-01 16:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 15:58 [for-linus][PATCH 00/12] tracing: Fixes for 5.10-rc6 Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 01/12] tools/bootconfig: Fix errno reference after printf() Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 02/12] tools/bootconfig: Fix to check the write failure correctly Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 03/12] tools/bootconfig: Align the bootconfig applied initrd image size to 4 Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 04/12] docs: bootconfig: Update file format on initrd image Steven Rostedt
2020-12-01 15:58 ` Steven Rostedt [this message]
2020-12-01 15:58 ` [for-linus][PATCH 06/12] ring-buffer: Set the right timestamp in the slow path of __rb_reserve_next() Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 07/12] samples/ftrace: Mark my_tramp[12]? global Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 08/12] tracing: Remove WARN_ON in start_thread() Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 09/12] tracing: Fix alignment of static buffer Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 10/12] ftrace: Fix updating FTRACE_FL_TRAMP Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 11/12] ftrace: Fix DYNAMIC_FTRACE_WITH_DIRECT_CALLS dependency Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 12/12] ring-buffer: Always check to put back before stamp when crossing pages Steven Rostedt
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