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| author | David S. Miller <davem@davemloft.net> | 2015-09-27 02:08:27 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-09-27 02:08:27 +0300 |
| commit | 4963ed48f2c20196d51a447ee87dc2815584fee4 (patch) | |
| tree | a1902f466dafa00453889a4f1e66b00249ce0529 /arch/x86/include/asm/qspinlock.h | |
| parent | 4d54d86546f62c7c4a0fe3b36a64c5e3b98ce1a9 (diff) | |
| parent | 518a7cb6980cd640c7f979d29021ad870f60d7d7 (diff) | |
| download | linux-4963ed48f2c20196d51a447ee87dc2815584fee4.tar.xz | |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Conflicts:
net/ipv4/arp.c
The net/ipv4/arp.c conflict was one commit adding a new
local variable while another commit was deleting one.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/x86/include/asm/qspinlock.h')
| -rw-r--r-- | arch/x86/include/asm/qspinlock.h | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/arch/x86/include/asm/qspinlock.h b/arch/x86/include/asm/qspinlock.h index 9d51fae1cba3..eaba08076030 100644 --- a/arch/x86/include/asm/qspinlock.h +++ b/arch/x86/include/asm/qspinlock.h @@ -39,18 +39,27 @@ static inline void queued_spin_unlock(struct qspinlock *lock) } #endif -#define virt_queued_spin_lock virt_queued_spin_lock - -static inline bool virt_queued_spin_lock(struct qspinlock *lock) +#ifdef CONFIG_PARAVIRT +#define virt_spin_lock virt_spin_lock +static inline bool virt_spin_lock(struct qspinlock *lock) { if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) return false; - while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0) - cpu_relax(); + /* + * On hypervisors without PARAVIRT_SPINLOCKS support we fall + * back to a Test-and-Set spinlock, because fair locks have + * horrible lock 'holder' preemption issues. + */ + + do { + while (atomic_read(&lock->val) != 0) + cpu_relax(); + } while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0); return true; } +#endif /* CONFIG_PARAVIRT */ #include <asm-generic/qspinlock.h> |