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Message-Id: <20070731113608.f2c5d8b6.akpm@linux-foundation.org>
Date: Tue, 31 Jul 2007 11:36:08 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: "Mike Frysinger" <vapier.adi@...il.com>
Cc: "Robin Getz" <rgetz@...ckfin.uclinux.org>,
linux-kernel@...r.kernel.org, "Greg Ungerer" <gerg@...pgear.com>,
"Russell King" <rmk@....linux.org.uk>,
"Paul Mundt" <lethal@...ux-sh.org>,
"Tim Bird" <tim.bird@...sony.com>, bryan.wu@...log.com
Subject: Re: early_printk accessing __log_buf
On Tue, 31 Jul 2007 03:47:59 -0400
"Mike Frysinger" <vapier.adi@...il.com> wrote:
> attached
> -mike
>
>
> [linux-log_buf_read.patch application/octet-stream (2.4KB)]
Please sort out the email thing if you plan on sending more kernel patches?
Incremental:
From: Andrew Morton <akpm@...ux-foundation.org>
- compile fix
- Race fix: oops_in_progress can change at any time
- coding-style fixlets.
Cc: Greg Ungerer <gerg@...pgear.com>
Cc: Mike Frysinger <vapier.adi@...il.com>
Cc: Mike Frysinger <vapier@...too.org>
Cc: Paul Mundt <lethal@...ux-sh.org>
Cc: Robin Getz <rgetz@...ckfin.uclinux.org>
Cc: Russell King <rmk@....linux.org.uk>
Cc: Tim Bird <tim.bird@...sony.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---
include/linux/kernel.h | 2 +-
kernel/printk.c | 12 ++++++++----
2 files changed, 9 insertions(+), 5 deletions(-)
diff -puN include/linux/kernel.h~early_printk-accessing-__log_buf-fix include/linux/kernel.h
--- a/include/linux/kernel.h~early_printk-accessing-__log_buf-fix
+++ a/include/linux/kernel.h
@@ -168,7 +168,7 @@ static inline int printk(const char *s,
__attribute__ ((format (printf, 1, 2)));
static inline int __cold printk(const char *s, ...) { return 0; }
static inline int log_buf_get_len(void) { return 0; }
-static inline int log_buf_read(int idx); { return 0; }
+static inline int log_buf_read(int idx) { return 0; }
static inline int log_buf_copy(char *dest, int idx, int len) { return 0; }
#endif
diff -puN kernel/printk.c~early_printk-accessing-__log_buf-fix kernel/printk.c
--- a/kernel/printk.c~early_printk-accessing-__log_buf-fix
+++ a/kernel/printk.c
@@ -233,14 +233,17 @@ int log_buf_get_len(void)
int log_buf_copy(char *dest, int idx, int len)
{
int ret, max;
+ bool took_lock = false;
- if (!oops_in_progress)
+ if (!oops_in_progress) {
spin_lock_irq(&logbuf_lock);
+ took_lock = true;
+ }
max = log_buf_get_len();
- if (idx < 0 || idx >= max)
+ if (idx < 0 || idx >= max) {
ret = -1;
- else {
+ } else {
if (len > max)
len = max;
ret = len;
@@ -250,7 +253,7 @@ int log_buf_copy(char *dest, int idx, in
}
}
- if (!oops_in_progress)
+ if (took_lock)
spin_unlock_irq(&logbuf_lock);
return ret;
@@ -262,6 +265,7 @@ int log_buf_copy(char *dest, int idx, in
int log_buf_read(int idx)
{
char ret;
+
if (log_buf_copy(&ret, idx, 1) == 1)
return ret;
else
_
-
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