Re: [PATCH] ARC: Improve cmpxchng syscall implementation

2018-04-18 Thread Vineet Gupta
On 03/21/2018 04:54 AM, Alexey Brodkin wrote: /* * This is only for old cores lacking LLOCK/SCOND, which by defintion @@ -60,23 +62,48 @@ SYSCALL_DEFINE3(arc_usr_cmpxchg, int *, uaddr, int, expected, int, new) /* Z indicates to userspace if operation succeded */

Re: [PATCH] ARC: Improve cmpxchng syscall implementation

2018-04-18 Thread Vineet Gupta
On 03/21/2018 04:54 AM, Alexey Brodkin wrote: /* * This is only for old cores lacking LLOCK/SCOND, which by defintion @@ -60,23 +62,48 @@ SYSCALL_DEFINE3(arc_usr_cmpxchg, int *, uaddr, int, expected, int, new) /* Z indicates to userspace if operation succeded */

Re: [PATCH] ARC: Improve cmpxchng syscall implementation

2018-04-04 Thread Alexey Brodkin
Hi Vineet, Peter, On Wed, 2018-03-21 at 14:54 +0300, Alexey Brodkin wrote: > Hi Vineet, > > On Mon, 2018-03-19 at 11:29 -0700, Vineet Gupta wrote: > > On 03/19/2018 04:00 AM, Alexey Brodkin wrote: > > > arc_usr_cmpxchg syscall is supposed to be used on platforms > > > that lack support of

Re: [PATCH] ARC: Improve cmpxchng syscall implementation

2018-04-04 Thread Alexey Brodkin
Hi Vineet, Peter, On Wed, 2018-03-21 at 14:54 +0300, Alexey Brodkin wrote: > Hi Vineet, > > On Mon, 2018-03-19 at 11:29 -0700, Vineet Gupta wrote: > > On 03/19/2018 04:00 AM, Alexey Brodkin wrote: > > > arc_usr_cmpxchg syscall is supposed to be used on platforms > > > that lack support of

Re: [PATCH] ARC: Improve cmpxchng syscall implementation

2018-03-21 Thread Alexey Brodkin
Hi Vineet, On Mon, 2018-03-19 at 11:29 -0700, Vineet Gupta wrote: > On 03/19/2018 04:00 AM, Alexey Brodkin wrote: > > arc_usr_cmpxchg syscall is supposed to be used on platforms > > that lack support of Load-Locked/Store-Conditional instructions > > in hardware. And in that case we mimic missing

Re: [PATCH] ARC: Improve cmpxchng syscall implementation

2018-03-21 Thread Alexey Brodkin
Hi Vineet, On Mon, 2018-03-19 at 11:29 -0700, Vineet Gupta wrote: > On 03/19/2018 04:00 AM, Alexey Brodkin wrote: > > arc_usr_cmpxchg syscall is supposed to be used on platforms > > that lack support of Load-Locked/Store-Conditional instructions > > in hardware. And in that case we mimic missing

Re: [PATCH] ARC: Improve cmpxchng syscall implementation

2018-03-19 Thread Vineet Gupta
On 03/19/2018 04:00 AM, Alexey Brodkin wrote: arc_usr_cmpxchg syscall is supposed to be used on platforms that lack support of Load-Locked/Store-Conditional instructions in hardware. And in that case we mimic missing hardware features with help of kernel's sycall that "atomically" checks current

Re: [PATCH] ARC: Improve cmpxchng syscall implementation

2018-03-19 Thread Vineet Gupta
On 03/19/2018 04:00 AM, Alexey Brodkin wrote: arc_usr_cmpxchg syscall is supposed to be used on platforms that lack support of Load-Locked/Store-Conditional instructions in hardware. And in that case we mimic missing hardware features with help of kernel's sycall that "atomically" checks current

[PATCH] ARC: Improve cmpxchng syscall implementation

2018-03-19 Thread Alexey Brodkin
arc_usr_cmpxchg syscall is supposed to be used on platforms that lack support of Load-Locked/Store-Conditional instructions in hardware. And in that case we mimic missing hardware features with help of kernel's sycall that "atomically" checks current value in memory and then if it matches caller

[PATCH] ARC: Improve cmpxchng syscall implementation

2018-03-19 Thread Alexey Brodkin
arc_usr_cmpxchg syscall is supposed to be used on platforms that lack support of Load-Locked/Store-Conditional instructions in hardware. And in that case we mimic missing hardware features with help of kernel's sycall that "atomically" checks current value in memory and then if it matches caller