a1c965da1e
Sixty-five headers sat side by side in include/, so `#include "irq.h"` said nothing about where irq.h was or what it belonged to, and errno.h, stat.h and fcntl.h at the top shadowed the system's for any host tool built with -I./include. They are in folders now -- arch/ core/ fs/ dev/ gfx/ net/ uapi/ (and ldls/ for the Linux driver layer) -- and every include names the folder, as Linux's do: "core/proc.h". Done mechanically and checked the hard way: the kernel built from this tree disassembles identically to the one built from the tree before it. The full image boots, and userland is the same set of programs. Paths in docs and comments follow; docs/guides/layout.md has a table of what is where, and tools/fix-includes.py rewrites old-style includes from the folders in the tree, for code written before this. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
74 lines
1.8 KiB
C
74 lines
1.8 KiB
C
// Sleeping locks
|
|
|
|
#include "core/types.h"
|
|
#include "core/defs.h"
|
|
#include "core/param.h"
|
|
#include "arch/x86.h"
|
|
#include "arch/memlayout.h"
|
|
#include "arch/mmu.h"
|
|
#include "core/proc.h"
|
|
#include "core/spinlock.h"
|
|
#include "core/sleeplock.h"
|
|
|
|
void
|
|
initsleeplock(struct sleeplock *lk, char *name)
|
|
{
|
|
initlock(&lk->lk, "sleep lock");
|
|
lk->name = name;
|
|
lk->locked = 0;
|
|
lk->pid = 0;
|
|
}
|
|
|
|
void
|
|
acquiresleep(struct sleeplock *lk)
|
|
{
|
|
acquire(&lk->lk);
|
|
while (lk->locked) {
|
|
sleep(lk, &lk->lk);
|
|
}
|
|
lk->locked = 1;
|
|
if (myproc()) {
|
|
lk->pid = myproc()->pid;
|
|
} else {
|
|
lk->pid = 0;
|
|
}
|
|
release(&lk->lk);
|
|
}
|
|
|
|
void
|
|
releasesleep(struct sleeplock *lk)
|
|
{
|
|
acquire(&lk->lk);
|
|
lk->locked = 0;
|
|
lk->pid = 0;
|
|
wakeup(lk);
|
|
release(&lk->lk);
|
|
}
|
|
|
|
// Does *this process* hold lk?
|
|
//
|
|
// The pid comparison is not decoration. Without it this answers "is anyone
|
|
// holding this", and every caller is an assertion of the form
|
|
//
|
|
// if (!holdingsleep(&b->lock)) panic("brelse");
|
|
//
|
|
// whose entire purpose is to catch a process releasing a lock it never took.
|
|
// Answering the weaker question disarms all seven of them: iunlock() on an
|
|
// inode locked by another process, and brelse() on somebody else's buffer,
|
|
// both sailed through and unlocked it underneath the real holder. Two
|
|
// processes then believe they hold the same inode, and the corruption surfaces
|
|
// somewhere else entirely -- which is exactly the shape of bug these panics
|
|
// exist to prevent.
|
|
//
|
|
// myproc() is null on the boot path before the scheduler runs, and
|
|
// acquiresleep() stores 0 for that case, so compare the same way rather than
|
|
// dereferencing null here.
|
|
int
|
|
holdingsleep(struct sleeplock *lk)
|
|
{
|
|
struct proc *p = myproc();
|
|
acquire(&lk->lk);
|
|
int r = lk->locked && lk->pid == (p ? p->pid : 0);
|
|
release(&lk->lk);
|
|
return r;
|
|
}
|