Messages in this thread | | | Subject | Re: random.c changes for sparse irq_desc are crap | From | Matt Mackall <> | Date | Wed, 31 Dec 2008 17:40:26 -0600 |
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On Wed, 2008-12-31 at 15:07 -0800, Yinghai Lu wrote: > Matt Mackall wrote: > > I just noticed you merged a change that pointlessly converts two > > random.c functions into ugly random.h inlines without going through the > > maintainer. > > > > I also don't like the look of the newly-introduced sparse variants of > > these functions. Failure to find an irq descriptor in > > get_timer_rand_state is a BUG_ON should-never-happen sort of condition, > > not something to silently ignore. Letting the code try to dereference > > NULL is preferred here: we'll actually be able to find and fix the > > broken driver that's throwing around meaningless irq vectors. > > > > Throwing away the timer_state pointer in the set_timer_rand_state > > function is similarly bogus in addition to being a memory leak. > > > > Please fix this up. > > > > want something like this?
Not quite.
First, please turn these back into normal functions in random.c. Inlining functions is generally discouraged these days unless you have a good reason and numbers to back it up.
Second, as I tried to explain above, BUG_ON(!desc) is doing very little that the subsequent desc->timer_rand_state wouldn't already do (generating a traceback). In cases where dereferencing NULL should never happen, it's preferable to not add the extra check and just let the oops happen. We'll still get a backtrace if anything ever goes wrong, but we won't have wasted any code space or CPU cycles when it doesn't.
-- Mathematics is the supreme nostalgia of our time.
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