linux-kernel - Re: [PATCH] idr: Print a stack dump after ida

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Message-Id: <20130507163422.7f88f07fc571b49362eb283a@linux-foundation.org>
Date:	Tue, 7 May 2013 16:34:22 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Jean Delvare <jdelvare@...e.de>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Tejun Heo <tj@...nel.org>, Takashi Iwai <tiwai@...e.de>
Subject: Re: [PATCH] idr: Print a stack dump after ida_remove warning

On Sun, 05 May 2013 11:32:03 +0200 Jean Delvare <jdelvare@...e.de> wrote:

> We print a dump stack after idr_remove warning. This is useful to find
> the faulty piece of code. Let's do the same for ida_remove, as it
> would be equally useful there.
> 
> ...
>
> --- linux-3.10-rc0.orig/lib/idr.c	2013-05-05 10:17:03.086198024 +0200
> +++ linux-3.10-rc0/lib/idr.c	2013-05-05 10:41:11.939134735 +0200
> @@ -1066,6 +1066,7 @@ void ida_remove(struct ida *ida, int id)
>   err:
>  	printk(KERN_WARNING
>  	       "ida_remove called for id=%d which is not allocated.\n", id);
> +	dump_stack();
>  }
>  EXPORT_SYMBOL(ida_remove);

If we're going to do this, we should make that printk a KERN_EMERG or
something, otherwise users might see a stack dump with no explanation
why it occurred.

We can do all that with plain old WARN().  How does this look?


From: Andrew Morton <akpm@...ux-foundation.org>
Subject: idr-print-a-stack-dump-after-ida_remove-warning-fix

convert the open-coded printk+dump_stack into WARN()

Cc: Jean Delvare <jdelvare@...e.de>
Cc: Takashi Iwai <tiwai@...e.de>
Cc: Tejun Heo <tj@...nel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---

 lib/idr.c |    8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff -puN lib/idr.c~idr-print-a-stack-dump-after-ida_remove-warning-fix lib/idr.c
--- a/lib/idr.c~idr-print-a-stack-dump-after-ida_remove-warning-fix
+++ a/lib/idr.c
@@ -524,9 +524,7 @@ EXPORT_SYMBOL(idr_alloc_cyclic);
 
 static void idr_remove_warning(int id)
 {
-	printk(KERN_WARNING
-		"idr_remove called for id=%d which is not allocated.\n", id);
-	dump_stack();
+	WARN(1, "idr_remove called for id=%d which is not allocated.\n", id);
 }
 
 static void sub_remove(struct idr *idp, int shift, int id)
@@ -1064,9 +1062,7 @@ void ida_remove(struct ida *ida, int id)
 	return;
 
  err:
-	printk(KERN_WARNING
-	       "ida_remove called for id=%d which is not allocated.\n", id);
-	dump_stack();
+	WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
 }
 EXPORT_SYMBOL(ida_remove);
 
_

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