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- Create a new lock, umtx_lock, for use instead of the proc lock for

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protecting the umtx queues.  We can't use the proc lock because we need
   to hold the lock across calls to casuptr, which can fault.

Approved by:	re
This commit is contained in:
Jeff Roberson 2003-05-25 18:18:32 +00:00
parent 43f0db6cc5
commit 0003d1b74e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=115310
1 changed files with 13 additions and 6 deletions
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19
sys/kern/kern_umtx.c
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@ -39,6 +39,13 @@
#include <sys/thr.h>
#include <sys/umtx.h>
#define UMTX_LOCK() mtx_lock(&umtx_lock);
#define UMTX_UNLOCK() mtx_unlock(&umtx_lock);
struct mtx umtx_lock;
MTX_SYSINIT(umtx, &umtx_lock, "User-land mutex lock", MTX_DEF);
int
_umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
/* struct umtx *umtx */
@ -57,7 +64,7 @@ _umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
*/
umtx = uap->umtx;
PROC_LOCK(td->td_proc);
UMTX_LOCK();
for (;;) {
/*
@ -103,7 +110,7 @@ _umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
}
/*
* We are now protected from further races via the proc lock.
* We are now protected from further races via umtx_lock.
* If userland messes with their mutex without using cmpset
* they will deadlock themselves but they will still be
* killable via signals.
@ -146,7 +153,7 @@ _umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
* used to maintain proper ordering.
*/
error = msleep(&td->td_umtx, &td->td_proc->p_mtx,
error = msleep(&td->td_umtx, &umtx_lock,
td->td_priority | PCATCH, "umtx", 0);
/*
@ -171,7 +178,7 @@ _umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
}
out:
PROC_UNLOCK(td->td_proc);
UMTX_UNLOCK();
return (error);
}
@ -190,7 +197,7 @@ _umtx_unlock(struct thread *td, struct _umtx_unlock_args *uap)
error = 0;
umtx = uap->umtx;
PROC_LOCK(td->td_proc);
UMTX_LOCK();
/*
* Make sure we own this mtx.
@ -300,7 +307,7 @@ _umtx_unlock(struct thread *td, struct _umtx_unlock_args *uap)
wakeup(&td0->td_umtx);
out:
PROC_UNLOCK(td->td_proc);
UMTX_UNLOCK();
return (error);
}