diff options
author | Frans Kaashoek <[email protected]> | 2017-01-31 20:21:14 -0500 |
---|---|---|
committer | Frans Kaashoek <[email protected]> | 2017-01-31 20:21:14 -0500 |
commit | fbb4c0944422f860484142010bb9f366f3e87bf8 (patch) | |
tree | 5e339842d43d09a4d23f1a2165391f00af30e308 /proc.c | |
parent | abf847a083888bbed4260ecacf849ea19f23e810 (diff) | |
download | xv6-labs-fbb4c0944422f860484142010bb9f366f3e87bf8.tar.gz xv6-labs-fbb4c0944422f860484142010bb9f366f3e87bf8.tar.bz2 xv6-labs-fbb4c0944422f860484142010bb9f366f3e87bf8.zip |
Read curproc from cpu structure, but be careful because after a schedule event
myproc() points to a different thread.
myproc();
sched();
myproc(); // this proc maybe different than the one before sched
Thus, in a function that operates on one thread better to retrieve the
current process once at the start of the function.
Diffstat (limited to 'proc.c')
-rw-r--r-- | proc.c | 101 |
1 files changed, 63 insertions, 38 deletions
@@ -26,14 +26,23 @@ pinit(void) initlock(&ptable.lock, "ptable"); } +// XXX get rid off? int cpuid() { return mycpu()-cpus; } -void -setproc(struct proc* p) { - mycpu()->proc = p; +// Disable interrupts so that we are not rescheduled +// while reading proc from the cpu structure +struct proc* +myproc(void) { + struct cpu *c; + struct proc *p; + pushcli(); + c = mycpu(); + p = c->proc; + popcli(); + return p; } //PAGEBREAK: 32 @@ -130,17 +139,18 @@ int growproc(int n) { uint sz; + struct proc *curproc = myproc(); - sz = myproc()->sz; + sz = curproc->sz; if(n > 0){ - if((sz = allocuvm(myproc()->pgdir, sz, sz + n)) == 0) + if((sz = allocuvm(curproc->pgdir, sz, sz + n)) == 0) return -1; } else if(n < 0){ - if((sz = deallocuvm(myproc()->pgdir, sz, sz + n)) == 0) + if((sz = deallocuvm(curproc->pgdir, sz, sz + n)) == 0) return -1; } - myproc()->sz = sz; - switchuvm(myproc()); + curproc->sz = sz; + switchuvm(curproc); return 0; } @@ -152,6 +162,7 @@ fork(void) { int i, pid; struct proc *np; + struct proc *curproc = myproc(); // Allocate process. if((np = allocproc()) == 0){ @@ -159,25 +170,25 @@ fork(void) } // Copy process state from proc. - if((np->pgdir = copyuvm(myproc()->pgdir, myproc()->sz)) == 0){ + if((np->pgdir = copyuvm(curproc->pgdir, curproc->sz)) == 0){ kfree(np->kstack); np->kstack = 0; np->state = UNUSED; return -1; } - np->sz = myproc()->sz; - np->parent = myproc(); - *np->tf = *myproc()->tf; + np->sz = curproc->sz; + np->parent = curproc; + *np->tf = *curproc->tf; // Clear %eax so that fork returns 0 in the child. np->tf->eax = 0; for(i = 0; i < NOFILE; i++) - if(myproc()->ofile[i]) - np->ofile[i] = filedup(myproc()->ofile[i]); - np->cwd = idup(myproc()->cwd); + if(curproc->ofile[i]) + np->ofile[i] = filedup(curproc->ofile[i]); + np->cwd = idup(curproc->cwd); - safestrcpy(np->name, myproc()->name, sizeof(myproc()->name)); + safestrcpy(np->name, curproc->name, sizeof(curproc->name)); pid = np->pid; @@ -196,33 +207,34 @@ fork(void) void exit(void) { + struct proc *curproc = myproc(); struct proc *p; int fd; - if(myproc() == initproc) + if(curproc == initproc) panic("init exiting"); // Close all open files. for(fd = 0; fd < NOFILE; fd++){ - if(myproc()->ofile[fd]){ - fileclose(myproc()->ofile[fd]); - myproc()->ofile[fd] = 0; + if(curproc->ofile[fd]){ + fileclose(curproc->ofile[fd]); + curproc->ofile[fd] = 0; } } begin_op(); - iput(myproc()->cwd); + iput(curproc->cwd); end_op(); - myproc()->cwd = 0; + curproc->cwd = 0; acquire(&ptable.lock); // Parent might be sleeping in wait(). - wakeup1(myproc()->parent); + wakeup1(curproc->parent); // Pass abandoned children to init. for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){ - if(p->parent == myproc()){ + if(p->parent == curproc){ p->parent = initproc; if(p->state == ZOMBIE) wakeup1(initproc); @@ -230,7 +242,7 @@ exit(void) } // Jump into the scheduler, never to return. - myproc()->state = ZOMBIE; + curproc->state = ZOMBIE; sched(); panic("zombie exit"); } @@ -242,13 +254,14 @@ wait(void) { struct proc *p; int havekids, pid; - + struct proc *curproc = myproc(); + acquire(&ptable.lock); for(;;){ // Scan through table looking for exited children. havekids = 0; for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){ - if(p->parent != myproc()) + if(p->parent != curproc) continue; havekids = 1; if(p->state == ZOMBIE){ @@ -268,13 +281,13 @@ wait(void) } // No point waiting if we don't have any children. - if(!havekids || myproc()->killed){ + if(!havekids || curproc->killed){ release(&ptable.lock); return -1; } // Wait for children to exit. (See wakeup1 call in proc_exit.) - sleep(myproc(), &ptable.lock); //DOC: wait-sleep + sleep(curproc, &ptable.lock); //DOC: wait-sleep } } @@ -290,6 +303,7 @@ void scheduler(void) { struct proc *p; + struct cpu *c = mycpu(); for(;;){ // Enable interrupts on this processor. @@ -304,15 +318,18 @@ scheduler(void) // Switch to chosen process. It is the process's job // to release ptable.lock and then reacquire it // before jumping back to us. - setproc(p); + c->proc = p; switchuvm(p); p->state = RUNNING; - swtch(&(mycpu()->scheduler), p->context); + p->cpu = c; + // cprintf("%d: switch to %d\n", c-cpus, p->pid); + swtch(&(p->cpu->scheduler), p->context); switchkvm(); // Process is done running for now. // It should have changed its p->state before coming back. - setproc(0); + c->proc = 0; + p->cpu = 0; } release(&ptable.lock); @@ -330,17 +347,20 @@ void sched(void) { int intena; + struct proc *p = myproc(); if(!holding(&ptable.lock)) panic("sched ptable.lock"); if(mycpu()->ncli != 1) panic("sched locks"); - if(myproc()->state == RUNNING) + if(p->state == RUNNING) panic("sched running"); if(readeflags()&FL_IF) panic("sched interruptible"); intena = mycpu()->intena; - swtch(&myproc()->context, mycpu()->scheduler); + // cprintf("%d: before swtch %d %x\n", p->cpu-cpus, p->pid, * (int *) 0x1d); + swtch(&p->context, p->cpu->scheduler); + // cprintf("%d/%d: after swtch %d %x\n", cpuid(), p->cpu-cpus, p->pid, * (int *) 0x1d); mycpu()->intena = intena; } @@ -380,7 +400,9 @@ forkret(void) void sleep(void *chan, struct spinlock *lk) { - if(myproc() == 0) + struct proc *p = myproc(); + + if(p == 0) panic("sleep"); if(lk == 0) @@ -397,12 +419,15 @@ sleep(void *chan, struct spinlock *lk) release(lk); } // Go to sleep. - myproc()->chan = chan; - myproc()->state = SLEEPING; + p->chan = chan; + p->state = SLEEPING; + + // cprintf("sleep %d\n", p->pid); + sched(); // Tidy up. - myproc()->chan = 0; + p->chan = 0; // Reacquire original lock. if(lk != &ptable.lock){ //DOC: sleeplock2 |