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Remove droping topology mutex after iterating 100 periphs in CAMGETPASSTHRU.

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That is not so slow and so often operation to handle unneeded otherwise
xsoftc.xpt_generation and respective locking complications.
This commit is contained in:
Alexander Motin 2013-08-07 11:34:20 +00:00
parent 02e4f2a3a4
commit a29779e865
3 changed files with 5 additions and 41 deletions
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4
sys/cam/cam_periph.c
View File

@ -258,7 +258,7 @@ cam_periph_alloc(periph_ctor_t *periph_ctor,
break;
case 3:
CAM_DEBUG(periph->path, CAM_DEBUG_INFO, ("Periph destroyed\n"));
xpt_remove_periph(periph, /*topology_lock_held*/ 0);
xpt_remove_periph(periph);
/* FALLTHROUGH */
case 2:
xpt_lock_buses();
@ -645,7 +645,7 @@ camperiphfree(struct cam_periph *periph)
TAILQ_REMOVE(&(*p_drv)->units, periph, unit_links);
(*p_drv)->generation++;
xpt_remove_periph(periph, /*topology_lock_held*/ 1);
xpt_remove_periph(periph);
xpt_unlock_buses();
CAM_DEBUG(periph->path, CAM_DEBUG_INFO, ("Periph destroyed\n"));

39
sys/cam/cam_xpt.c
View File

@ -96,7 +96,6 @@ typedef enum {
struct xpt_softc {
xpt_flags flags;
u_int32_t xpt_generation;
/* number of high powered commands that can go through right now */
STAILQ_HEAD(highpowerlist, cam_ed) highpowerq;
@ -608,24 +607,11 @@ xptdoioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flag, struct thread *
struct periph_driver **p_drv;
char *name;
u_int unit;
u_int cur_generation;
int base_periph_found;
int splbreaknum;
ccb = (union ccb *)addr;
unit = ccb->cgdl.unit_number;
name = ccb->cgdl.periph_name;
/*
* Every 100 devices, we want to drop our lock protection to
* give the software interrupt handler a chance to run.
* Most systems won't run into this check, but this should
* avoid starvation in the software interrupt handler in
* large systems.
*/
splbreaknum = 100;
ccb = (union ccb *)addr;
base_periph_found = 0;
/*
@ -639,8 +625,6 @@ xptdoioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flag, struct thread *
/* Keep the list from changing while we traverse it */
xpt_lock_buses();
ptstartover:
cur_generation = xsoftc.xpt_generation;
/* first find our driver in the list of drivers */
for (p_drv = periph_drivers; *p_drv != NULL; p_drv++)
@ -667,15 +651,8 @@ xptdoioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flag, struct thread *
for (periph = TAILQ_FIRST(&(*p_drv)->units); periph != NULL;
periph = TAILQ_NEXT(periph, unit_links)) {
if (periph->unit_number == unit) {
if (periph->unit_number == unit)
break;
} else if (--splbreaknum == 0) {
xpt_unlock_buses();
xpt_lock_buses();
splbreaknum = 100;
if (cur_generation != xsoftc.xpt_generation)
goto ptstartover;
}
}
/*
* If we found the peripheral driver that the user passed
@ -1015,15 +992,11 @@ xpt_add_periph(struct cam_periph *periph)
SLIST_INSERT_HEAD(periph_head, periph, periph_links);
}
xpt_lock_buses();
xsoftc.xpt_generation++;
xpt_unlock_buses();
return (status);
}
void
xpt_remove_periph(struct cam_periph *periph, int topology_lock_held)
xpt_remove_periph(struct cam_periph *periph)
{
struct cam_ed *device;
@ -1043,14 +1016,6 @@ xpt_remove_periph(struct cam_periph *periph, int topology_lock_held)
SLIST_REMOVE(periph_head, periph, cam_periph, periph_links);
}
if (topology_lock_held == 0)
xpt_lock_buses();
xsoftc.xpt_generation++;
if (topology_lock_held == 0)
xpt_unlock_buses();
}

3
sys/cam/cam_xpt_periph.h
View File

@ -42,8 +42,7 @@ void xpt_polled_action(union ccb *ccb);
void xpt_release_ccb(union ccb *released_ccb);
void xpt_schedule(struct cam_periph *perph, u_int32_t new_priority);
int32_t xpt_add_periph(struct cam_periph *periph);
void xpt_remove_periph(struct cam_periph *periph,
int topology_lock_held);
void xpt_remove_periph(struct cam_periph *periph);
void xpt_announce_periph(struct cam_periph *periph,
char *announce_string);
void xpt_announce_quirks(struct cam_periph *periph,