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kernel: generalize awake

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Awake can now interrupt several blocking syscalls (even
during note handling).

Among others, it can interrupt await, pread and pwrite.

It cannot interrupt several others for different reasons:

- awake cannot be interrupted by awake;
- syscalls like remove and create can be used for kernel comunication
  and it would be hard to know if the effect occurred in the
  receiving fs if they were interrupted;
- other syscalls do not need awake since they just provide access
  to kernel infos (eg seek or fd2path)

NOTE: awakes registered before a note cannot occur during the note
handling and will be deferred till the next call to noted.
This commit is contained in:
Giacomo Tesio
2017-05-15 00:05:59 +02:00
parent 79f8204766
commit f9b2e9aba4
9 changed files with 132 additions and 115 deletions
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67
sys/src/kern/port/sysproc.c
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@ -1,7 +1,7 @@
/*
* This file is part of Jehanne.
*
* Copyright (C) 2015-2016 Giacomo Tesio <giacomo@tesio.it>
* Copyright (C) 2015-2017 Giacomo Tesio <giacomo@tesio.it>
*
* Jehanne is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@ -858,7 +858,6 @@ sysrendezvous(void* tagp, void* rendvalp)
result = UINT2PTR(up->rendval);
rendezvousDone:
awokeproc(up);
return result;
}
@ -1061,50 +1060,6 @@ semacquire(ProcSegment* s, int* addr, int block)
return 1;
}
/* Acquire semaphore or time-out */
static int
tsemacquire(ProcSegment* s, int* addr, uint64_t ms)
{
int acquired, timedout;
uint64_t t, elms;
Sema phore;
if(canacquire(addr))
return 1;
if(ms == 0)
return 0;
acquired = timedout = 0;
semqueue(s, addr, &phore);
for(;;){
phore.waiting = 1;
coherence();
if(canacquire(addr)){
acquired = 1;
break;
}
if(waserror())
break;
t = sys->ticks;
tsleep(&phore.rend, semawoke, &phore, ms);
elms = TK2MS(sys->ticks - t);
poperror();
if(elms >= ms){
timedout = 1;
break;
}
ms -= elms;
}
semdequeue(s, &phore);
coherence(); /* not strictly necessary due to lock in semdequeue */
if(!phore.waiting)
semwakeup(s, addr, 1);
if(timedout)
return 0;
if(!acquired)
nexterror();
return 1;
}
int
syssemacquire(int* addr, int block)
{
@ -1124,26 +1079,6 @@ syssemacquire(int* addr, int block)
return semacquire(s, addr, block);
}
int
systsemacquire(int* addr, uint64_t ms)
{
ProcSegment *s;
addr = validaddr(addr, sizeof(int), 1);
evenaddr(PTR2UINT(addr));
s = proc_segment(up, PTR2UINT(addr));
if(s == nil || (s->permissions&SgWrite) == 0 || (uintptr_t)addr+sizeof(int) > s->top){
validaddr(addr, sizeof(int), 1);
error(Ebadarg);
}
if(*addr < 0)
error(Ebadarg);
return tsemacquire(s, addr, ms);
}
int
syssemrelease(int* addr, int delta)
{