percpu: Generic support for this_cpu_cmpxchg_double()
Introduce this_cpu_cmpxchg_double(). this_cpu_cmpxchg_double() allows
the comparison between two consecutive words and replaces them if
there is a match.
bool this_cpu_cmpxchg_double(pcp1, pcp2,
old_word1, old_word2, new_word1, new_word2)
this_cpu_cmpxchg_double does not return the old value (difficult since
there are two words) but a boolean indicating if the operation was
successful.
The first percpu variable must be double word aligned!
-tj: Updated to return bool instead of int, converted size check to
BUILD_BUG_ON() instead of VM_BUG_ON() and other cosmetic changes.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Christoph Lameter
Tejun Heo
parent
0f06c06362
commit
7c33433921
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@ -255,6 +255,30 @@ extern void __bad_size_call_parameter(void);
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pscr2_ret__; \
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})
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/*
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* Special handling for cmpxchg_double. cmpxchg_double is passed two
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* percpu variables. The first has to be aligned to a double word
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* boundary and the second has to follow directly thereafter.
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*/
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#define __pcpu_double_call_return_bool(stem, pcp1, pcp2, ...) \
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({ \
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bool pdcrb_ret__; \
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__verify_pcpu_ptr(&pcp1); \
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BUILD_BUG_ON(sizeof(pcp1) != sizeof(pcp2)); \
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VM_BUG_ON((unsigned long)(&pcp1) % (2 * sizeof(pcp1))); \
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VM_BUG_ON((unsigned long)(&pcp2) != \
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(unsigned long)(&pcp1) + sizeof(pcp1)); \
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switch(sizeof(pcp1)) { \
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case 1: pdcrb_ret__ = stem##1(pcp1, pcp2, __VA_ARGS__); break; \
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case 2: pdcrb_ret__ = stem##2(pcp1, pcp2, __VA_ARGS__); break; \
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case 4: pdcrb_ret__ = stem##4(pcp1, pcp2, __VA_ARGS__); break; \
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case 8: pdcrb_ret__ = stem##8(pcp1, pcp2, __VA_ARGS__); break; \
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default: \
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__bad_size_call_parameter(); break; \
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} \
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pdcrb_ret__; \
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})
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#define __pcpu_size_call(stem, variable, ...) \
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do { \
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__verify_pcpu_ptr(&(variable)); \
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@ -500,6 +524,45 @@ do { \
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__pcpu_size_call_return2(this_cpu_cmpxchg_, pcp, oval, nval)
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#endif
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/*
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* cmpxchg_double replaces two adjacent scalars at once. The first
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* two parameters are per cpu variables which have to be of the same
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* size. A truth value is returned to indicate success or failure
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* (since a double register result is difficult to handle). There is
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* very limited hardware support for these operations, so only certain
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* sizes may work.
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*/
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#define _this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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({ \
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int ret__; \
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preempt_disable(); \
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ret__ = __this_cpu_generic_cmpxchg_double(pcp1, pcp2, \
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oval1, oval2, nval1, nval2); \
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preempt_enable(); \
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ret__; \
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})
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#ifndef this_cpu_cmpxchg_double
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# ifndef this_cpu_cmpxchg_double_1
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# define this_cpu_cmpxchg_double_1(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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_this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# ifndef this_cpu_cmpxchg_double_2
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# define this_cpu_cmpxchg_double_2(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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_this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# ifndef this_cpu_cmpxchg_double_4
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# define this_cpu_cmpxchg_double_4(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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_this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# ifndef this_cpu_cmpxchg_double_8
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# define this_cpu_cmpxchg_double_8(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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_this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# define this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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__pcpu_double_call_return_bool(this_cpu_cmpxchg_double_, (pcp1), (pcp2), (oval1), (oval2), (nval1), (nval2))
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#endif
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/*
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* Generic percpu operations that do not require preemption handling.
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* Either we do not care about races or the caller has the
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@ -703,6 +766,39 @@ do { \
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__pcpu_size_call_return2(__this_cpu_cmpxchg_, pcp, oval, nval)
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#endif
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#define __this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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({ \
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int __ret = 0; \
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if (__this_cpu_read(pcp1) == (oval1) && \
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__this_cpu_read(pcp2) == (oval2)) { \
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__this_cpu_write(pcp1, (nval1)); \
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__this_cpu_write(pcp2, (nval2)); \
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__ret = 1; \
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} \
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(__ret); \
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})
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#ifndef __this_cpu_cmpxchg_double
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# ifndef __this_cpu_cmpxchg_double_1
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# define __this_cpu_cmpxchg_double_1(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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__this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# ifndef __this_cpu_cmpxchg_double_2
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# define __this_cpu_cmpxchg_double_2(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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__this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# ifndef __this_cpu_cmpxchg_double_4
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# define __this_cpu_cmpxchg_double_4(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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__this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# ifndef __this_cpu_cmpxchg_double_8
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# define __this_cpu_cmpxchg_double_8(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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__this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# define __this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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__pcpu_double_call_return_bool(__this_cpu_cmpxchg_double_, (pcp1), (pcp2), (oval1), (oval2), (nval1), (nval2))
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#endif
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/*
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* IRQ safe versions of the per cpu RMW operations. Note that these operations
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* are *not* safe against modification of the same variable from another
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@ -823,4 +919,36 @@ do { \
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__pcpu_size_call_return2(irqsafe_cpu_cmpxchg_, (pcp), oval, nval)
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#endif
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#define irqsafe_generic_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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({ \
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int ret__; \
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unsigned long flags; \
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local_irq_save(flags); \
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ret__ = __this_cpu_generic_cmpxchg_double(pcp1, pcp2, \
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oval1, oval2, nval1, nval2); \
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local_irq_restore(flags); \
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ret__; \
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})
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#ifndef irqsafe_cpu_cmpxchg_double
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# ifndef irqsafe_cpu_cmpxchg_double_1
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# define irqsafe_cpu_cmpxchg_double_1(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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irqsafe_generic_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# ifndef irqsafe_cpu_cmpxchg_double_2
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# define irqsafe_cpu_cmpxchg_double_2(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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irqsafe_generic_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# ifndef irqsafe_cpu_cmpxchg_double_4
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# define irqsafe_cpu_cmpxchg_double_4(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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irqsafe_generic_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# ifndef irqsafe_cpu_cmpxchg_double_8
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# define irqsafe_cpu_cmpxchg_double_8(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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irqsafe_generic_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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# endif
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# define irqsafe_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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__pcpu_double_call_return_int(irqsafe_cpu_cmpxchg_double_, (pcp1), (pcp2), (oval1), (oval2), (nval1), (nval2))
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#endif
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#endif /* __LINUX_PERCPU_H */
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