* bdevname(), cdevname(), kdevname() - static buffers
@ 2001-11-02 18:42 Russ Weight
2001-11-02 18:59 ` Alan Cox
2001-11-02 19:03 ` Andreas Dilger
0 siblings, 2 replies; 3+ messages in thread
From: Russ Weight @ 2001-11-02 18:42 UTC (permalink / raw)
To: linux-kernel
Hi,
I was looking at the usage of bdevname(), cdevname(), and kdevname(),
and noticed that they each return a pointer to a static buffer.
This buffer contains a formatted device name, which is typically
printed immediately following the call. However, I don't see any
explicit lock protection for these buffers.
For SMP systems, is there something implicit in their use that
prevents a race on these buffers? Has anyone seen garbled device
names being printed (which might be attributed to a race)?
- Russ
----------------------------------------------------------------------
Russ Weight (rweight@us.ibm.com)
IBM Technology Center
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: bdevname(), cdevname(), kdevname() - static buffers
2001-11-02 18:42 bdevname(), cdevname(), kdevname() - static buffers Russ Weight
@ 2001-11-02 18:59 ` Alan Cox
2001-11-02 19:03 ` Andreas Dilger
1 sibling, 0 replies; 3+ messages in thread
From: Alan Cox @ 2001-11-02 18:59 UTC (permalink / raw)
To: Russ Weight; +Cc: linux-kernel
> I was looking at the usage of bdevname(), cdevname(), and kdevname(),
> and noticed that they each return a pointer to a static buffer.
> This buffer contains a formatted device name, which is typically
> printed immediately following the call. However, I don't see any
> explicit lock protection for these buffers.
>
> For SMP systems, is there something implicit in their use that
> prevents a race on these buffers? Has anyone seen garbled device
> names being printed (which might be attributed to a race)?
Not currently, other than statistics being on our side. It probably should
be touched up in 2.4 to use per cpu buffers and perhaps 2.5 pass a buffer
in
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: bdevname(), cdevname(), kdevname() - static buffers
2001-11-02 18:42 bdevname(), cdevname(), kdevname() - static buffers Russ Weight
2001-11-02 18:59 ` Alan Cox
@ 2001-11-02 19:03 ` Andreas Dilger
1 sibling, 0 replies; 3+ messages in thread
From: Andreas Dilger @ 2001-11-02 19:03 UTC (permalink / raw)
To: Russ Weight; +Cc: linux-kernel
On Nov 02, 2001 10:42 -0800, Russ Weight wrote:
> I was looking at the usage of bdevname(), cdevname(), and kdevname(),
> and noticed that they each return a pointer to a static buffer.
> This buffer contains a formatted device name, which is typically
> printed immediately following the call. However, I don't see any
> explicit lock protection for these buffers.
>
> For SMP systems, is there something implicit in their use that
> prevents a race on these buffers? Has anyone seen garbled device
> names being printed (which might be attributed to a race)?
I think the general usage of these is only for informational needs, so
if there is a rare race it is not worth fixing.
Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/
^ permalink raw reply [flat|nested] 3+ messages in thread
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2001-11-02 18:42 bdevname(), cdevname(), kdevname() - static buffers Russ Weight
2001-11-02 18:59 ` Alan Cox
2001-11-02 19:03 ` Andreas Dilger
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