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Close a pesky race where after checking the BUSY flag in amr_wait_command,

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the completion of the command can occur before tsleep is called and
the command ends up blocking forever since the wakeup has already
been called.

Submitted by:   ups
This commit is contained in:
Paul Saab 2006-04-08 02:23:27 +00:00
parent 07c8931358
commit 026d2aa333
3 changed files with 21 additions and 6 deletions
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25
sys/dev/amr/amr.c
View File

@ -383,6 +383,9 @@ amr_free(struct amr_softc *sc)
if (mtx_initialized(&sc->amr_list_lock))
mtx_destroy(&sc->amr_list_lock);
if (mtx_initialized(&sc->amr_wait_lock))
mtx_destroy(&sc->amr_wait_lock);
}
/*******************************************************************************
@ -1322,7 +1325,8 @@ static int
amr_wait_command(struct amr_command *ac)
{
int error = 0;
struct amr_softc *sc = ac->ac_sc;
debug_called(1);
ac->ac_complete = NULL;
@ -1331,9 +1335,12 @@ amr_wait_command(struct amr_command *ac)
return(error);
}
mtx_lock(&sc->amr_wait_lock);
while ((ac->ac_flags & AMR_CMD_BUSY) && (error != EWOULDBLOCK)) {
error = tsleep(ac, PRIBIO, "amrwcmd", 0);
error = msleep(ac,&sc->amr_wait_lock, PRIBIO, "amrwcmd", 0);
}
mtx_unlock(&sc->amr_wait_lock);
return(error);
}
@ -1995,21 +2002,27 @@ amr_complete(void *context, int pending)
/* unmap the command's data buffer */
amr_unmapcmd(ac);
/* unbusy the command */
ac->ac_flags &= ~AMR_CMD_BUSY;
/*
* Is there a completion handler?
*/
if (ac->ac_complete != NULL) {
/* unbusy the command */
ac->ac_flags &= ~AMR_CMD_BUSY;
ac->ac_complete(ac);
/*
* Is someone sleeping on this one?
*/
} else if (ac->ac_flags & AMR_CMD_SLEEP) {
mtx_lock(&sc->amr_wait_lock);
/* unbusy the command */
ac->ac_flags &= ~AMR_CMD_BUSY;
mtx_unlock(&sc->amr_wait_lock);
wakeup(ac);
}
} else {
/* unbusy the command */
ac->ac_flags &= ~AMR_CMD_BUSY;
}
if(!sc->amr_busyslots) {
wakeup(sc);

1
sys/dev/amr/amr_pci.c
View File

@ -331,6 +331,7 @@ amr_pci_attach(device_t dev)
*/
mtx_init(&sc->amr_list_lock, "AMR List Lock", NULL, MTX_DEF);
mtx_init(&sc->amr_hw_lock, "AMR HW Lock", NULL, MTX_DEF);
mtx_init(&sc->amr_wait_lock, "AMR Wait Lock", NULL, MTX_DEF);
if ((error = amr_setup_mbox(sc)) != 0)
goto out;

1
sys/dev/amr/amrvar.h
View File

@ -244,6 +244,7 @@ struct amr_softc
int amr_linux_no_adapters;
int amr_ld_del_supported;
struct mtx amr_hw_lock;
struct mtx amr_wait_lock;
};
/*