Messages in this thread | | | Date | Tue, 15 Apr 2008 22:17:07 -0700 | From | Andrew Morton <> | Subject | Re: [Linux-fbdev-devel] [PATCH] fb: Remove use of lock_kernel / unlock_kernel in fbmem |
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On Sun, 13 Apr 2008 11:50:07 -0300 Thiago Galesi <thiagogalesi@gmail.com> wrote:
> This patch removes lock_kernel(), unlock_kernel() usage in fbmem.c and replaces it with a mutex
It isn't that simple, alas.
vfs_ioctl() runs lock_kernel() prior to calling fb_ioctl(), so the lock_kernel()s in fb_compat_ioctl() are actually providing exclusion against fb_ioctl(). Your patch would break that.
A suitable fix might be to do
__fb_ioctl(...) { <copy fb_ioctl() into here> }
fb_ioctl(...) { mutex_lock(&info->hwlock); __fb_ioctl(...); mutex_unlock(&info->hwlock); }
and then change fb_compat_ioctl() to call __fb_ioctl(). All the other callers of fb_ioctl() would need to be reviewed - see if they need to take the mutex then call __fb_ioctl(), or they might be OK as they are, calling fb_ioctl().
Then we can switch fb_fops over to
.ioctl = NULL, .unlocked_ioctl = fb_ioctl,
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