Andrew Morton wrote:
Linus Torvalds <[email protected]> wrote:
> On Mon, 22 Oct 2007, Matthew Wilcox wrote:
> > We certainly don't want to encourage people to blindly make those
> > conversions ... and I've seen the results of encouraging kernel janitors
> > to do things a certain way.
> There's another issue: the "irqsave/irqrestore" versions are much safer
> than the plain "irq" versions, in case the caller already has interrupts
> disabled.
It's almost always a bug to do spin_lock_irq() when local interrupts are
disabled.
Let me add to the chorus of voices: I continually see two cases where
real bugs crop up:
1) hacker uses spin_lock_irq() in incorrect context (where it is not
safe to do a blind enable/disable)
2) hacker uses spin_lock_irq() correctly, but the surrounding code
changes, thus invalidating prior assumptions.
I would even go so far as to support the drastic measure of deleting
spin_lock_irq().
spin_lock_irqsave() generates fewer bugs, is more future-proof, and by
virtue of 'flags' permits architectures a bit more flexibility.
Jeff
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