Messages in this thread | | | Date | Thu, 12 Feb 2015 19:55:42 +0530 | From | Raghavendra K T <> | Subject | Re: [PATCH V3] x86 spinlock: Fix memory corruption on completing completions |
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On 02/12/2015 07:32 PM, Oleg Nesterov wrote: > Damn, sorry for noise, forgot to mention... > > On 02/12, Raghavendra K T wrote: >> >> +static inline void __ticket_check_and_clear_slowpath(arch_spinlock_t *lock, >> + __ticket_t head) >> +{ >> + if (head & TICKET_SLOWPATH_FLAG) { >> + arch_spinlock_t old, new; >> + >> + old.tickets.head = head; >> + new.tickets.head = head & ~TICKET_SLOWPATH_FLAG; >> + old.tickets.tail = new.tickets.head + TICKET_LOCK_INC; >> + new.tickets.tail = old.tickets.tail; >> + >> + /* try to clear slowpath flag when there are no contenders */ >> + cmpxchg(&lock->head_tail, old.head_tail, new.head_tail); >> + } >> +} > > ... > >> +clear_slowpath: >> + if (TICKET_SLOWPATH_FLAG) >> + __ticket_check_and_clear_slowpath(lock, inc.head); > > I think you can remove this "if (TICKET_SLOWPATH_FLAG)" check. If it is > defined as zero, gcc should optimize out the code under "if (head & 0)". >
right, the above if ( ) is unnecesary, though we would have same code at the end, getting rid of that makes code more clean.
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