> It could (nearly) be replaced with nothing at all. There is
> little benefit though. In usbdev_open, the BKL is only
> being used to protect dev->filelist, even if at first it seems
> that it is protecting against a race with disconnect -
> namely the possibility of dev being changed to null under
> you. Why is there no race with disconnect? Because
> the disconnect code holds the BKL and usbdev_open
> does not sleep (after the kmalloc at least; good catch
> by the way). So the value of dev does not change. So
> what is the BKL being used for? As far as I can see it is
> being used to serialize access to dev->filelist and that is
> all. Usually a spin lock is used for such tasks, but hey!
> this is not a critical code path.
So in your oppinion, the patch should be applied?
Regards
Oliver
PS: Greg, here it is for your benefit again,
should you want to apply it
You can import this changeset into BK by piping this whole message to:
'| bk receive [path to repository]' or apply the patch as usual.
===================================================================
[EMAIL PROTECTED], 2002-12-08 13:42:36+01:00, [EMAIL PROTECTED]
- fix race between disconnect and usbdev_open
devio.c | 12 ++++++++----
1 files changed, 8 insertions(+), 4 deletions(-)
diff -Nru a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
--- a/drivers/usb/core/devio.c Sun Dec 8 13:44:21 2002
+++ b/drivers/usb/core/devio.c Sun Dec 8 13:44:21 2002
@@ -484,14 +484,17 @@
* and the hub thread have the kernel lock
* (still acquire the kernel lock for safety)
*/
+ ret = -ENOMEM;
+ if (!(ps = kmalloc(sizeof(struct dev_state), GFP_KERNEL)))
+ goto out_nolock;
+
lock_kernel();
ret = -ENOENT;
dev = inode->u.generic_ip;
- if (!dev)
- goto out;
- ret = -ENOMEM;
- if (!(ps = kmalloc(sizeof(struct dev_state), GFP_KERNEL)))
+ if (!dev) {
+ kfree(ps);
goto out;
+ }
ret = 0;
ps->dev = dev;
ps->file = file;
@@ -509,6 +512,7 @@
file->private_data = ps;
out:
unlock_kernel();
+ out_nolock:
return ret;
}
===================================================================
This BitKeeper patch contains the following changesets:
1.1084
## Wrapped with gzip_uu ##
begin 664 bkpatch5819
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M"8-/&U,O>[NSX!8(?RJ\,HWSV/=\O(=1_7GW>HPO]V[)`<?AC-$(./F!G,D#
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M2OK3>H^2AP0ZA!0A$Q!D4'<W%XRF[]Z_G;X])@,S@Z.?CM:--R[+W6J.&O,K
MVME1X^J-K^-=`6^<<CC\&5Z_NKP^GUZ]FUX,AT,R&,RM)]YNW'5E_<#E,?E(
M7HJ,^GG.1-:!V8?W(8;PF^^_G/E[UT\V/.XZ"&!D\#LYBQGSK3MQQK=7\D[-
39E-.<BEC7]8D^0.W>"Q*_P<`````
`
end
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