Author: imp
Date: Tue Aug 25 06:25:59 2009
New Revision: 196529
URL: http://svn.freebsd.org/changeset/base/196529
Log:
Rather than havnig enabled/disabled, implement a max queue depth.
While usually not an issue, this firewalls bugs in the code that may
run us out of memory.
Fix a memory exhaustion in the case where devctl was disabled, but the
link was bouncing. The check to queue was in the wrong place.
Implement a new sysctl hw.bus.devctl_queue to control the depth. Make
compatibility hacks for hw.bus.devctl_disable to ease transition.
Reviewed by: emaste@
Approved by: re@ (kib)
MFC after: asap
Modified:
head/sys/kern/subr_bus.c
Modified: head/sys/kern/subr_bus.c
==============================================================================
--- head/sys/kern/subr_bus.c Tue Aug 25 06:21:45 2009 (r196528)
+++ head/sys/kern/subr_bus.c Tue Aug 25 06:25:59 2009 (r196529)
@@ -350,11 +350,18 @@ device_sysctl_fini(device_t dev)
* tested since 3.4 or 2.2.8!
*/
+/* Deprecated way to adjust queue length */
static int sysctl_devctl_disable(SYSCTL_HANDLER_ARGS);
-static int devctl_disable = 0;
-TUNABLE_INT("hw.bus.devctl_disable", &devctl_disable);
+/* XXX Need to support old-style tunable hw.bus.devctl_disable" */
SYSCTL_PROC(_hw_bus, OID_AUTO, devctl_disable, CTLTYPE_INT | CTLFLAG_RW, NULL,
- 0, sysctl_devctl_disable, "I", "devctl disable");
+ 0, sysctl_devctl_disable, "I", "devctl disable -- deprecated");
+
+#define DEVCTL_DEFAULT_QUEUE_LEN 1000
+static int sysctl_devctl_queue(SYSCTL_HANDLER_ARGS);
+static int devctl_queue_length = DEVCTL_DEFAULT_QUEUE_LEN;
+TUNABLE_INT("hw.bus.devctl_queue", &devctl_queue_length);
+SYSCTL_PROC(_hw_bus, OID_AUTO, devctl_queue, CTLTYPE_INT | CTLFLAG_RW, NULL,
+ 0, sysctl_devctl_queue, "I", "devctl queue length");
static d_open_t devopen;
static d_close_t devclose;
@@ -385,6 +392,7 @@ static struct dev_softc
{
int inuse;
int nonblock;
+ int queued;
struct mtx mtx;
struct cv cv;
struct selinfo sel;
@@ -423,7 +431,7 @@ devclose(struct cdev *dev, int fflag, in
mtx_lock(&devsoftc.mtx);
cv_broadcast(&devsoftc.cv);
mtx_unlock(&devsoftc.mtx);
-
+ devsoftc.async_proc = NULL;
return (0);
}
@@ -458,6 +466,7 @@ devread(struct cdev *dev, struct uio *ui
}
n1 = TAILQ_FIRST(&devsoftc.devq);
TAILQ_REMOVE(&devsoftc.devq, n1, dei_link);
+ devsoftc.queued--;
mtx_unlock(&devsoftc.mtx);
rv = uiomove(n1->dei_data, strlen(n1->dei_data), uio);
free(n1->dei_data, M_BUS);
@@ -531,21 +540,33 @@ devctl_process_running(void)
void
devctl_queue_data(char *data)
{
- struct dev_event_info *n1 = NULL;
+ struct dev_event_info *n1 = NULL, *n2 = NULL;
struct proc *p;
- /*
- * Do not allow empty strings to be queued, as they
- * cause devd to exit prematurely.
- */
if (strlen(data) == 0)
return;
+ if (devctl_queue_length == 0)
+ return;
n1 = malloc(sizeof(*n1), M_BUS, M_NOWAIT);
if (n1 == NULL)
return;
n1->dei_data = data;
mtx_lock(&devsoftc.mtx);
+ if (devctl_queue_length == 0) {
+ free(n1->dei_data, M_BUS);
+ free(n1, M_BUS);
+ return;
+ }
+ /* Leave at least one spot in the queue... */
+ while (devsoftc.queued > devctl_queue_length - 1) {
+ n2 = TAILQ_FIRST(&devsoftc.devq);
+ TAILQ_REMOVE(&devsoftc.devq, n2, dei_link);
+ free(n2->dei_data, M_BUS);
+ free(n2, M_BUS);
+ devsoftc.queued--;
+ }
TAILQ_INSERT_TAIL(&devsoftc.devq, n1, dei_link);
+ devsoftc.queued++;
cv_broadcast(&devsoftc.cv);
mtx_unlock(&devsoftc.mtx);
selwakeup(&devsoftc.sel);
@@ -614,7 +635,7 @@ devaddq(const char *type, const char *wh
char *pnp = NULL;
const char *parstr;
- if (devctl_disable)
+ if (!devctl_queue_length)/* Rare race, but lost races safely discard */
return;
data = malloc(1024, M_BUS, M_NOWAIT);
if (data == NULL)
@@ -731,12 +752,11 @@ sysctl_devctl_disable(SYSCTL_HANDLER_ARG
struct dev_event_info *n1;
int dis, error;
- dis = devctl_disable;
+ dis = devctl_queue_length == 0;
error = sysctl_handle_int(oidp, &dis, 0, req);
if (error || !req->newptr)
return (error);
mtx_lock(&devsoftc.mtx);
- devctl_disable = dis;
if (dis) {
while (!TAILQ_EMPTY(&devsoftc.devq)) {
n1 = TAILQ_FIRST(&devsoftc.devq);
@@ -744,6 +764,35 @@ sysctl_devctl_disable(SYSCTL_HANDLER_ARG
free(n1->dei_data, M_BUS);
free(n1, M_BUS);
}
+ devsoftc.queued = 0;
+ devctl_queue_length = 0;
+ } else {
+ devctl_queue_length = DEVCTL_DEFAULT_QUEUE_LEN;
+ }
+ mtx_unlock(&devsoftc.mtx);
+ return (0);
+}
+
+static int
+sysctl_devctl_queue(SYSCTL_HANDLER_ARGS)
+{
+ struct dev_event_info *n1;
+ int q, error;
+
+ q = devctl_queue_length;
+ error = sysctl_handle_int(oidp, &q, 0, req);
+ if (error || !req->newptr)
+ return (error);
+ if (q < 0)
+ return (EINVAL);
+ mtx_lock(&devsoftc.mtx);
+ devctl_queue_length = q;
+ while (devsoftc.queued > devctl_queue_length) {
+ n1 = TAILQ_FIRST(&devsoftc.devq);
+ TAILQ_REMOVE(&devsoftc.devq, n1, dei_link);
+ free(n1->dei_data, M_BUS);
+ free(n1, M_BUS);
+ devsoftc.queued--;
}
mtx_unlock(&devsoftc.mtx);
return (0);
@@ -886,7 +935,7 @@ devclass_find_internal(const char *class
if (create && !dc) {
PDEBUG(("creating %s", classname));
dc = malloc(sizeof(struct devclass) + strlen(classname) + 1,
- M_BUS, M_NOWAIT|M_ZERO);
+ M_BUS, M_NOWAIT | M_ZERO);
if (!dc)
return (NULL);
dc->parent = NULL;
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