Ingo Molnar wrote:
* Jim Cromie <[email protected]> wrote:
btw '?' carries *is this really what you want ?* connotations. Is
that intended ? If not, maybe '=' is better.. 2 lines --> 'both'
well i dont see '=' any better than '?'.
let me rephrase.
for someone who knows intimately what they mean, how the flags are
rendered is unimportant.
but for someone who is looking to understand what lockdep
errors/messages mean,
they may look for hints in the the choice of flag-char, which could
convey 'severity'
! - something went bang, oh shit
* - splatted on landing
? - huh? - did you mean to do this ?
_ - blank, unspecified ..
It could be that making any such inferences is looking for hints that
dont exist,
otoh - if some messages are more severe, it would make sense to connote
that in the
choice of symbols to represent the flags/states.
IOW, were I to find a lockdep errmsg with {--??} vs {--..} in dmesg,
would it warrant any extra attention (as in *fix-me-first*) ? or just
investigated
[ btw.: truly '....' locks are candiates for optimization, as they
unnecessarily disable interrupts in process context. ]
is that a future optimization, needing another pair of
functions/macros ?
it means they dont really have to be spin_lock_irq()/spin_unlock_irq()
uses but spin_lock()/spin_unlock() would be enough. (but it's not
guaranted - some rare codepath that has not triggered yet might use
those locks from IRQ context, at which point the irq-safety in process
context is compulsory.)
Thats helpful. So continuing this line..
If joe-hacker were to falsely optimize, and then trigger the rare path
later,
would the lockdep errmsg contain { ??}, or do I oversimplify ?
Ingo
thanks
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