Messages in this thread | | | Date | Wed, 14 May 2008 14:56:37 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [announce] "kill the Big Kernel Lock (BKL)" tree |
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On Wed, 14 May 2008, Jonathan Corbet wrote: > > There's also every char device open() method - a rather long list in its > own right. I'd be surprised if one in ten of them really needs it, but > one has to look...
I don't think there are *that* many. I found only 83 instances of "register_chrdev()" in the kernel, so the open methods should be pretty limited.
Of course, some open methods call other sub-registrations, but you'd start off by moving the lock_kernel() down just *one* stage.
So it literally should be: - remove one lock_kernel/unlock_kernel pair in fs/char_dev.c - add max 83 pairs in the places that register those things - external modules will need to add it themselves some day.
> 1: We could add an unlocked_open() to the file_operations structure; > drivers could be converted over as they are verified not to need the > BKL on open. Disadvantages are that it grows this structure for a > relatively rare case - most open() calls already don't need the BKL. > But it's a relatively easy path without flag days.
I really don't think it's worth the pain. See above. The numbers aren't that huge, and external modules simply aren't a pressing enough issue.
Linus
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