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* [PATCH] printk: Clean up do_syslog() error handling
@ 2017-07-30  3:36 Nikitas Angelinas
  2017-08-01  7:38 ` Sergey Senozhatsky
  2017-08-15 15:03 ` Petr Mladek
  0 siblings, 2 replies; 3+ messages in thread
From: Nikitas Angelinas @ 2017-07-30  3:36 UTC (permalink / raw)
  To: Petr Mladek, Sergey Senozhatsky, Steven Rostedt
  Cc: linux-kernel, nikitas.angelinas

The error variable in do_syslog() is preemptively set to the error code
before the error condition is checked, and then set to 0 if the error
condition is not encountered. This is not necessary, as it is likely
simpler to return immediately upon encountering the error condition. A
redundant set of the error variable to 0 is also removed.

This patch has been build-tested on x86_64, but not tested for
functionality.

Signed-off-by: Nikitas Angelinas <nikitas.angelinas@gmail.com>
---
 kernel/printk/printk.c | 35 ++++++++++++-----------------------
 1 file changed, 12 insertions(+), 23 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 87f1a8f4e0f9..cfd9ab1b80c5 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1435,7 +1435,7 @@ int do_syslog(int type, char __user *buf, int len, int source)
 
 	error = check_syslog_permissions(type, source);
 	if (error)
-		goto out;
+		return error;
 
 	switch (type) {
 	case SYSLOG_ACTION_CLOSE:	/* Close log */
@@ -1443,20 +1443,16 @@ int do_syslog(int type, char __user *buf, int len, int source)
 	case SYSLOG_ACTION_OPEN:	/* Open log */
 		break;
 	case SYSLOG_ACTION_READ:	/* Read from log */
-		error = -EINVAL;
 		if (!buf || len < 0)
-			goto out;
-		error = 0;
+			return -EINVAL;
 		if (!len)
-			goto out;
-		if (!access_ok(VERIFY_WRITE, buf, len)) {
-			error = -EFAULT;
-			goto out;
-		}
+			return 0;
+		if (!access_ok(VERIFY_WRITE, buf, len))
+			return -EFAULT;
 		error = wait_event_interruptible(log_wait,
 						 syslog_seq != log_next_seq);
 		if (error)
-			goto out;
+			return error;
 		error = syslog_print(buf, len);
 		break;
 	/* Read/clear last kernel messages */
@@ -1465,16 +1461,12 @@ int do_syslog(int type, char __user *buf, int len, int source)
 		/* FALL THRU */
 	/* Read last kernel messages */
 	case SYSLOG_ACTION_READ_ALL:
-		error = -EINVAL;
 		if (!buf || len < 0)
-			goto out;
-		error = 0;
+			return -EINVAL;
 		if (!len)
-			goto out;
-		if (!access_ok(VERIFY_WRITE, buf, len)) {
-			error = -EFAULT;
-			goto out;
-		}
+			return 0;
+		if (!access_ok(VERIFY_WRITE, buf, len))
+			return -EFAULT;
 		error = syslog_print_all(buf, len, clear);
 		break;
 	/* Clear ring buffer */
@@ -1496,15 +1488,13 @@ int do_syslog(int type, char __user *buf, int len, int source)
 		break;
 	/* Set level of messages printed to console */
 	case SYSLOG_ACTION_CONSOLE_LEVEL:
-		error = -EINVAL;
 		if (len < 1 || len > 8)
-			goto out;
+			return -EINVAL;
 		if (len < minimum_console_loglevel)
 			len = minimum_console_loglevel;
 		console_loglevel = len;
 		/* Implicitly re-enable logging to console */
 		saved_console_loglevel = LOGLEVEL_DEFAULT;
-		error = 0;
 		break;
 	/* Number of chars in the log buffer */
 	case SYSLOG_ACTION_SIZE_UNREAD:
@@ -1526,7 +1516,6 @@ int do_syslog(int type, char __user *buf, int len, int source)
 			u64 seq = syslog_seq;
 			u32 idx = syslog_idx;
 
-			error = 0;
 			while (seq < log_next_seq) {
 				struct printk_log *msg = log_from_idx(idx);
 
@@ -1546,7 +1535,7 @@ int do_syslog(int type, char __user *buf, int len, int source)
 		error = -EINVAL;
 		break;
 	}
-out:
+
 	return error;
 }
 
-- 
2.11.1

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] printk: Clean up do_syslog() error handling
  2017-07-30  3:36 [PATCH] printk: Clean up do_syslog() error handling Nikitas Angelinas
@ 2017-08-01  7:38 ` Sergey Senozhatsky
  2017-08-15 15:03 ` Petr Mladek
  1 sibling, 0 replies; 3+ messages in thread
From: Sergey Senozhatsky @ 2017-08-01  7:38 UTC (permalink / raw)
  To: Nikitas Angelinas
  Cc: Petr Mladek, Sergey Senozhatsky, Steven Rostedt, linux-kernel

On (07/29/17 20:36), Nikitas Angelinas wrote:
> The error variable in do_syslog() is preemptively set to the error code
> before the error condition is checked, and then set to 0 if the error
> condition is not encountered. This is not necessary, as it is likely
> simpler to return immediately upon encountering the error condition. A
> redundant set of the error variable to 0 is also removed.
> 
> This patch has been build-tested on x86_64, but not tested for
> functionality.
> 
> Signed-off-by: Nikitas Angelinas <nikitas.angelinas@gmail.com>

looks good to me,

Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>



// p.s. Petr is on vacation now

	-ss

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] printk: Clean up do_syslog() error handling
  2017-07-30  3:36 [PATCH] printk: Clean up do_syslog() error handling Nikitas Angelinas
  2017-08-01  7:38 ` Sergey Senozhatsky
@ 2017-08-15 15:03 ` Petr Mladek
  1 sibling, 0 replies; 3+ messages in thread
From: Petr Mladek @ 2017-08-15 15:03 UTC (permalink / raw)
  To: Nikitas Angelinas; +Cc: Sergey Senozhatsky, Steven Rostedt, linux-kernel

On Sat 2017-07-29 20:36:36, Nikitas Angelinas wrote:
> The error variable in do_syslog() is preemptively set to the error code
> before the error condition is checked, and then set to 0 if the error
> condition is not encountered. This is not necessary, as it is likely
> simpler to return immediately upon encountering the error condition. A
> redundant set of the error variable to 0 is also removed.
> 
> This patch has been build-tested on x86_64, but not tested for
> functionality.
> 
> Signed-off-by: Nikitas Angelinas <nikitas.angelinas@gmail.com>

The code looks better. Also the patch looks correct.

Acked-by: Petr Mladek <pmladek@suse.com>

I have pushed it into for-4.14 branch.

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2017-08-15 15:03 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2017-07-30  3:36 [PATCH] printk: Clean up do_syslog() error handling Nikitas Angelinas
2017-08-01  7:38 ` Sergey Senozhatsky
2017-08-15 15:03 ` Petr Mladek

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