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Implement CAM_PERIPH_FOREACH() macro, safely iterating over the list of

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driver's periphs, acquiring and releaseing periph references while doing it.

Use it to iterate over the lists of ada and da periphs when flushing caches
and putting devices to sleep on shutdown and suspend.  Previous code could
panic in theory if some device disappear in the middle of the process.
This commit is contained in:
Alexander Motin 2013-03-29 07:50:47 +00:00
parent 10e00ec8cc
commit f371c9e260
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=248868
3 changed files with 43 additions and 4 deletions
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6
sys/cam/ata/ata_da.c
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@ -1835,7 +1835,7 @@ adaflush(void)
struct ada_softc *softc;
int error;
TAILQ_FOREACH(periph, &adadriver.units, unit_links) {
CAM_PERIPH_FOREACH(periph, &adadriver) {
union ccb ccb;
/* If we paniced with lock held - not recurse here. */
@ -1889,7 +1889,7 @@ adaspindown(uint8_t cmd, int flags)
struct ada_softc *softc;
int error;
TAILQ_FOREACH(periph, &adadriver.units, unit_links) {
CAM_PERIPH_FOREACH(periph, &adadriver) {
union ccb ccb;
/* If we paniced with lock held - not recurse here. */
@ -1962,7 +1962,7 @@ adaresume(void *arg)
if (ada_spindown_suspend == 0)
return;
TAILQ_FOREACH(periph, &adadriver.units, unit_links) {
CAM_PERIPH_FOREACH(periph, &adadriver) {
cam_periph_lock(periph);
softc = (struct ada_softc *)periph->softc;
/*

39
sys/cam/cam_periph.h
View File

@ -183,6 +183,8 @@ void cam_periph_freeze_after_event(struct cam_periph *periph,
u_int duration_ms);
int cam_periph_error(union ccb *ccb, cam_flags camflags,
u_int32_t sense_flags, union ccb *save_ccb);
void xpt_lock_buses(void);
void xpt_unlock_buses(void);
static __inline void
cam_periph_lock(struct cam_periph *periph)
@ -209,5 +211,42 @@ cam_periph_sleep(struct cam_periph *periph, void *chan, int priority,
return (msleep(chan, periph->sim->mtx, priority, wmesg, timo));
}
static inline struct cam_periph *
cam_periph_acquire_first(struct periph_driver *driver)
{
struct cam_periph *periph;
xpt_lock_buses();
periph = TAILQ_FIRST(&driver->units);
while (periph != NULL && (periph->flags & CAM_PERIPH_INVALID) != 0)
periph = TAILQ_NEXT(periph, unit_links);
if (periph != NULL)
periph->refcount++;
xpt_unlock_buses();
return (periph);
}
static inline struct cam_periph *
cam_periph_acquire_next(struct cam_periph *pperiph)
{
struct cam_periph *periph = pperiph;
mtx_assert(pperiph->sim->mtx, MA_NOTOWNED);
xpt_lock_buses();
do {
periph = TAILQ_NEXT(periph, unit_links);
} while (periph != NULL && (periph->flags & CAM_PERIPH_INVALID) != 0);
if (periph != NULL)
periph->refcount++;
xpt_unlock_buses();
cam_periph_release(pperiph);
return (periph);
}
#define CAM_PERIPH_FOREACH(periph, driver) \
for ((periph) = cam_periph_acquire_first(driver); \
(periph) != NULL; \
(periph) = cam_periph_acquire_next(periph))
#endif /* _KERNEL */
#endif /* _CAM_CAM_PERIPH_H */

2
sys/cam/scsi/scsi_da.c
View File

@ -2848,7 +2848,7 @@ dashutdown(void * arg, int howto)
struct da_softc *softc;
int error;
TAILQ_FOREACH(periph, &dadriver.units, unit_links) {
CAM_PERIPH_FOREACH(periph, &dadriver) {
union ccb ccb;
cam_periph_lock(periph);