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Add SIM refcounting. This is slightly different from what DragonFly

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does - in DragonFly, it's cam_sim_release() what actually frees the
SIM; cam_sim_free does nothing more than calling cam_sim_release().
Here, we drain in cam_sim_free, waiting for refcount to drop to zero.
We cannot do the same think DragonFly does, because after cam_sim_free
returns, client would destroy the sim->mtx, and CAM would trip over
an initialized mutex.

Reviewed by:	scottl
Approved by:	rwatson (mentor)
Sponsored by:	FreeBSD Foundation
This commit is contained in:
Edward Tomasz Napierala 2008-12-16 16:57:33 +00:00
parent 96100101a8
commit fa6099fda0
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=186185
3 changed files with 34 additions and 0 deletions
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29
sys/cam/cam_sim.c
View File

@ -84,6 +84,7 @@ cam_sim_alloc(sim_action_func sim_action, sim_poll_func sim_poll,
sim->max_tagged_dev_openings = max_tagged_dev_transactions;
sim->max_dev_openings = max_dev_transactions;
sim->flags = 0;
sim->refcount = 1;
sim->devq = queue;
sim->mtx = mtx;
if (mtx == &Giant) {
@ -103,11 +104,39 @@ cam_sim_alloc(sim_action_func sim_action, sim_poll_func sim_poll,
void
cam_sim_free(struct cam_sim *sim, int free_devq)
{
int error;
sim->refcount--;
if (sim->refcount > 0) {
error = msleep(sim, sim->mtx, PRIBIO, "simfree", 0);
KASSERT(error == 0, ("invalid error value for msleep(9)"));
}
KASSERT(sim->refcount == 0, ("sim->refcount == 0"));
if (free_devq)
cam_simq_free(sim->devq);
free(sim, M_CAMSIM);
}
void
cam_sim_release(struct cam_sim *sim)
{
KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
sim->refcount--;
if (sim->refcount <= 1)
wakeup(sim);
}
void
cam_sim_hold(struct cam_sim *sim)
{
KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
sim->refcount++;
}
void
cam_sim_set_path(struct cam_sim *sim, u_int32_t path_id)
{

3
sys/cam/cam_sim.h
View File

@ -61,6 +61,8 @@ struct cam_sim * cam_sim_alloc(sim_action_func sim_action,
int max_tagged_dev_transactions,
struct cam_devq *queue);
void cam_sim_free(struct cam_sim *sim, int free_devq);
void cam_sim_hold(struct cam_sim *sim);
void cam_sim_release(struct cam_sim *sim);
/* Optional sim attributes may be set with these. */
void cam_sim_set_path(struct cam_sim *sim, u_int32_t path_id);
@ -105,6 +107,7 @@ struct cam_sim {
#define CAM_SIM_ON_DONEQ 0x04
struct callout callout;
struct cam_devq *devq; /* Device Queue to use for this SIM */
int refcount; /* References to the SIM. */
/* "Pool" of inactive ccbs managed by xpt_alloc_ccb and xpt_free_ccb */
SLIST_HEAD(,ccb_hdr) ccb_freeq;

2
sys/cam/cam_xpt.c
View File

@ -4304,6 +4304,7 @@ xpt_bus_register(struct cam_sim *sim, device_t parent, u_int32_t bus)
TAILQ_INIT(&new_bus->et_entries);
new_bus->path_id = sim->path_id;
cam_sim_hold(sim);
new_bus->sim = sim;
timevalclear(&new_bus->last_reset);
new_bus->flags = 0;
@ -4846,6 +4847,7 @@ xpt_release_bus(struct cam_eb *bus)
TAILQ_REMOVE(&xsoftc.xpt_busses, bus, links);
xsoftc.bus_generation++;
mtx_unlock(&xsoftc.xpt_topo_lock);
cam_sim_release(bus->sim);
free(bus, M_CAMXPT);
}
}