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Message-ID: <tip-93cfb3c9fd83d877a8f1ffad9ff862b617b32828@git.kernel.org>
Date: Fri, 10 Apr 2009 11:07:24 GMT
From: Lai Jiangshan <laijs@...fujitsu.com>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
fweisbec@...il.com, srostedt@...hat.com, tglx@...utronix.de,
laijs@...fujitsu.com, mingo@...e.hu
Subject: [tip:tracing/core] tracing: fix splice return too large
Commit-ID: 93cfb3c9fd83d877a8f1ffad9ff862b617b32828
Gitweb: http://git.kernel.org/tip/93cfb3c9fd83d877a8f1ffad9ff862b617b32828
Author: Lai Jiangshan <laijs@...fujitsu.com>
AuthorDate: Thu, 2 Apr 2009 15:17:08 +0800
Committer: Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 10 Apr 2009 12:44:46 +0200
tracing: fix splice return too large
I got these from strace:
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 16384
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192
I wanted to splice_read 4096 bytes, but it returns 8192 or larger.
It is because the return value of tracing_buffers_splice_read()
does not include "zero out any left over data" bytes.
But tracing_buffers_read() includes these bytes, we make them
consistent.
Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Steven Rostedt <srostedt@...hat.com>
LKML-Reference: <49D46674.9030804@...fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
kernel/trace/trace.c | 16 ++++++++++++++--
1 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9462976..1ce5dc6 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3428,7 +3428,19 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
int size, i;
size_t ret;
- for (i = 0; i < PIPE_BUFFERS && len; i++, len -= size) {
+ if (*ppos & (PAGE_SIZE - 1)) {
+ WARN_ONCE(1, "Ftrace: previous read must page-align\n");
+ return -EINVAL;
+ }
+
+ if (len & (PAGE_SIZE - 1)) {
+ WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
+ if (len < PAGE_SIZE)
+ return -EINVAL;
+ len &= PAGE_MASK;
+ }
+
+ for (i = 0; i < PIPE_BUFFERS && len; i++, len -= PAGE_SIZE) {
struct page *page;
int r;
@@ -3467,7 +3479,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
spd.partial[i].offset = 0;
spd.partial[i].private = (unsigned long)ref;
spd.nr_pages++;
- *ppos += size;
+ *ppos += PAGE_SIZE;
}
spd.nr_pages = i;
--
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