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Spinlock definitionSpinlock definitionPosted Feb 2, 2012 11:39 UTC (Thu) by abacus (guest, #49001)Parent article: Betrayed by a bitfield
From
typedef u8 __ticket_t;
typedef u16 __ticketpair_t;
typedef struct arch_spinlock {
union {
__ticketpair_t head_tail;
struct __raw_tickets {
__ticket_t head, tail;
} tickets;
};
} arch_spinlock_t;
Shouldn't all the above fields have been declared as volatile ?
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Spinlock definition Posted Feb 3, 2012 6:54 UTC (Fri) by ncm (subscriber, #165) [Link]
No, volatile almost never does anything useful. It's the 32-bit lock word that was the mistake. Fortunately, it should be easy to fix in the kernel without depending on a compiler fix, just by forcing a 64-bit aligned word.
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