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kernel: insert memory barrier in the scheduler before setting up->mach = nil

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we have to ensure that all stores saving the process state
have completed before setting up->mach = nil in the scheduler.
otherwise, another cpu could observe up->mach == nil while
the stores such as the processes p->sched label have not finnished.
This commit is contained in:
cinap_lenrek 2019-05-01 09:35:51 +02:00
parent 97a2f14b1c
commit 54562b6ac2
1 changed files with 5 additions and 2 deletions
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7
sys/src/9/port/proc.c
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@ -70,6 +70,9 @@ schedinit(void) /* never returns */
edfrecord(up); edfrecord(up);
m->proc = nil; m->proc = nil;
switch(up->state) { switch(up->state) {
default:
updatecpu(up);
break;
case Running: case Running:
ready(up); ready(up);
break; break;
@ -88,8 +91,8 @@ schedinit(void) /* never returns */
mmurelease(up); mmurelease(up);
unlock(&palloc); unlock(&palloc);
up->mach = nil;
updatecpu(up); updatecpu(up);
up->mach = nil;
up->qnext = procalloc.free; up->qnext = procalloc.free;
procalloc.free = up; procalloc.free = up;
@ -99,8 +102,8 @@ schedinit(void) /* never returns */
unlock(&procalloc); unlock(&procalloc);
sched(); sched();
} }
coherence();
up->mach = nil; up->mach = nil;
updatecpu(up);
up = nil; up = nil;
} }
sched(); sched();