| Message ID | 1468487697-12705-1-git-send-email-czuzu@bitdefender.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 14/07/16 10:14, Corneliu ZUZU wrote: > - implement missing functions atomic_{sub,inc,dec}_return(), atomic_add_unless() > on X86 and also add prototypes for them in common <xen/atomic.h> > > - add missing macro atomic_xchg for X86 > > Signed-off-by: Corneliu ZUZU <czuzu@bitdefender.com> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
On 7/14/2016 12:29 PM, Andrew Cooper wrote: > On 14/07/16 10:14, Corneliu ZUZU wrote: >> - implement missing functions atomic_{sub,inc,dec}_return(), atomic_add_unless() >> on X86 and also add prototypes for them in common <xen/atomic.h> >> >> - add missing macro atomic_xchg for X86 >> >> Signed-off-by: Corneliu ZUZU<czuzu@bitdefender.com> > > Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> I'm not sure about atomic_sub_return(int i, atomic_t *v) implementation - is it ok? (calling arch_fetch_and_add(&v->counter, -i) with 2nd argument negative). Zuzu C.
On 14/07/16 10:39, Corneliu ZUZU wrote: > On 7/14/2016 12:29 PM, Andrew Cooper wrote: >> On 14/07/16 10:14, Corneliu ZUZU wrote: >>> - implement missing functions atomic_{sub,inc,dec}_return(), atomic_add_unless() >>> on X86 and also add prototypes for them in common <xen/atomic.h> >>> >>> - add missing macro atomic_xchg for X86 >>> >>> Signed-off-by: Corneliu ZUZU <czuzu@bitdefender.com> >> >> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> > > I'm not sure about atomic_sub_return(int i, atomic_t *v) > implementation - is it ok? (calling arch_fetch_and_add(&v->counter, > -i) with 2nd argument negative). Looks ok to me. Everything is signed integers in the internals. There is a boundary condition when passing INT_MIN, but those exist elsewhere as well. ~Andrew
On 7/14/2016 12:44 PM, Andrew Cooper wrote: > On 14/07/16 10:39, Corneliu ZUZU wrote: >> On 7/14/2016 12:29 PM, Andrew Cooper wrote: >>> On 14/07/16 10:14, Corneliu ZUZU wrote: >>>> - implement missing functions atomic_{sub,inc,dec}_return(), atomic_add_unless() >>>> on X86 and also add prototypes for them in common <xen/atomic.h> >>>> >>>> - add missing macro atomic_xchg for X86 >>>> >>>> Signed-off-by: Corneliu ZUZU<czuzu@bitdefender.com> >>> >>> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> >> >> I'm not sure about atomic_sub_return(int i, atomic_t *v) >> implementation - is it ok? (calling arch_fetch_and_add(&v->counter, >> -i) with 2nd argument negative). > > Looks ok to me. Everything is signed integers in the internals. > > There is a boundary condition when passing INT_MIN, but those exist > elsewhere as well. > > ~Andrew Thanks, thought so too - there should be no difference bit-wise when adding an unsigned int converted from an int vs adding the int directly. Zuzu C.
diff --git a/xen/include/asm-x86/atomic.h b/xen/include/asm-x86/atomic.h index 1729e29..101eded 100644 --- a/xen/include/asm-x86/atomic.h +++ b/xen/include/asm-x86/atomic.h @@ -126,6 +126,11 @@ static inline void atomic_sub(int i, atomic_t *v) : "ir" (i), "m" (*(volatile int *)&v->counter) ); } +static inline int atomic_sub_return(int i, atomic_t *v) +{ + return arch_fetch_and_add(&v->counter, -i) - i; +} + static inline int atomic_sub_and_test(int i, atomic_t *v) { unsigned char c; @@ -145,6 +150,11 @@ static inline void atomic_inc(atomic_t *v) : "m" (*(volatile int *)&v->counter) ); } +static inline int atomic_inc_return(atomic_t *v) +{ + return atomic_add_return(1, v); +} + static inline int atomic_inc_and_test(atomic_t *v) { unsigned char c; @@ -164,6 +174,11 @@ static inline void atomic_dec(atomic_t *v) : "m" (*(volatile int *)&v->counter) ); } +static inline int atomic_dec_return(atomic_t *v) +{ + return atomic_sub_return(1, v); +} + static inline int atomic_dec_and_test(atomic_t *v) { unsigned char c; @@ -186,4 +201,16 @@ static inline int atomic_add_negative(int i, atomic_t *v) return c; } +static inline int atomic_add_unless(atomic_t *v, int a, int u) +{ + int c, old; + + c = atomic_read(v); + while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c) + c = old; + return c; +} + +#define atomic_xchg(v, new) (xchg(&((v)->counter), new)) + #endif /* __ARCH_X86_ATOMIC__ */ diff --git a/xen/include/xen/atomic.h b/xen/include/xen/atomic.h index 6827468..529213e 100644 --- a/xen/include/xen/atomic.h +++ b/xen/include/xen/atomic.h @@ -111,6 +111,15 @@ static inline int atomic_add_return(int i, atomic_t *v); static inline void atomic_sub(int i, atomic_t *v); /** + * atomic_sub_return - sub integer and return + * @i: integer value to sub + * @v: pointer of type atomic_t + * + * Atomically subtracts @i from @v and returns @v - @i. + */ +static inline int atomic_sub_return(int i, atomic_t *v); + +/** * atomic_sub_and_test - subtract value from variable and test result * @i: integer value to subtract * @v: pointer of type atomic_t @@ -130,6 +139,14 @@ static inline int atomic_sub_and_test(int i, atomic_t *v); static inline void atomic_inc(atomic_t *v); /** + * atomic_inc_return - increment atomic variable and return + * @v: pointer of type atomic_t + * + * Atomically increments @v by 1 and returns @v + 1. + */ +static inline int atomic_inc_return(atomic_t *v); + +/** * atomic_inc_and_test - increment and test * @v: pointer of type atomic_t * @@ -148,6 +165,14 @@ static inline int atomic_inc_and_test(atomic_t *v); static inline void atomic_dec(atomic_t *v); /** + * atomic_dec_return - decrement atomic variable and return + * @v: pointer of type atomic_t + * + * Atomically decrements @v by 1 and returns @v - 1. + */ +static inline int atomic_dec_return(atomic_t *v); + +/** * atomic_dec_and_test - decrement and test * @v: pointer of type atomic_t * @@ -168,4 +193,15 @@ static inline int atomic_dec_and_test(atomic_t *v); */ static inline int atomic_add_negative(int i, atomic_t *v); +/** + * atomic_add_unless - add to atomic variable unless it has a specified value + * @v: pointer of type atomic_t + * @a: integer value to add + * @u: integer value @v must -not- be for the add to be performed + * + * If @v != @u, adds @a to @v and returns @v + @a. + * Otherwise returns @u (== @v). + */ +static inline int atomic_add_unless(atomic_t *v, int a, int u); + #endif /* __XEN_ATOMIC_H__ */
- implement missing functions atomic_{sub,inc,dec}_return(), atomic_add_unless() on X86 and also add prototypes for them in common <xen/atomic.h> - add missing macro atomic_xchg for X86 Signed-off-by: Corneliu ZUZU <czuzu@bitdefender.com> --- xen/include/asm-x86/atomic.h | 27 +++++++++++++++++++++++++++ xen/include/xen/atomic.h | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 63 insertions(+)