Author: jamie
Date: Wed Mar 30 16:57:28 2016
New Revision: 297422
URL: https://svnweb.freebsd.org/changeset/base/297422
Log:
Add osd_reserve() and osd_set_reserved(), which allow M_WAITOK allocation
of an OSD array,
Modified:
head/share/man/man9/osd.9
head/sys/kern/kern_osd.c
head/sys/sys/osd.h
Modified: head/share/man/man9/osd.9
==============================================================================
--- head/share/man/man9/osd.9 Wed Mar 30 16:54:18 2016 (r297421)
+++ head/share/man/man9/osd.9 Wed Mar 30 16:57:28 2016 (r297422)
@@ -25,7 +25,7 @@
.\"
.\" $FreeBSD$
.\"
-.Dd January 5, 2011
+.Dd March 30, 2016
.Dt OSD 9
.Os
.Sh NAME
@@ -33,6 +33,9 @@
.Nm osd_register ,
.Nm osd_deregister ,
.Nm osd_set ,
+.Nm osd_reserve ,
+.Nm osd_set_reserved ,
+.Nm osd_free_reserved ,
.Nm osd_get ,
.Nm osd_del ,
.Nm osd_call ,
@@ -63,6 +66,22 @@
.Fa "void *value"
.Fc
.Ft void *
+.Fo osd_reserve
+.Fa "u_int slot"
+.Fc
+.Ft int
+.Fo osd_set_reserved
+.Fa "u_int type"
+.Fa "struct osd *osd"
+.Fa "u_int slot"
+.Fa "void *rsv"
+.Fa "void *value"
+.Fc
+.Ft void
+.Fo osd_free_reserved
+.Fa "void *rsv"
+.Fc
+.Ft void *
.Fo osd_get
.Fa "u_int type"
.Fa "struct osd *osd"
@@ -198,6 +217,15 @@ argument points to a data object to asso
.Fa osd .
.Pp
The
+.Fn osd_set_reserved
+function does the same as
+.Fn osd_set ,
+but with an extra argument
+.Fa rsv
+that is internal-use memory previously allocated via
+.Fn osd_reserve .
+.Pp
+The
.Fn osd_get
function returns the data pointer associated with a kernel data structure's
.Vt struct osd
@@ -324,6 +352,24 @@ will proceed without any
.Xr realloc 9
calls.
.Pp
+It is possible for
+.Fn osd_set
+to fail to allocate this array. To ensure that such allocation succeeds,
+.Fn osd_reserve
+may be called (in a non-blocking context), and it will pre-allocate the
+memory via
+.Xr malloc 9
+with M_WAITOK.
+Then this pre-allocated memory is passed to
+.Fn osd_set_reserved ,
+which will use it if necessary or otherwise discard it.
+The memory may also be explicitly discarded by calling
+.Fn osd_free_reserved .
+As this method always allocates memory whether or not it is ultimately needed,
+it should be used only rarely, such as in the unlikely event that
+.Fn osd_set
+fails.
+.Pp
The
.Nm
API is geared towards slot identifiers storing pointers to the same underlying
@@ -359,15 +405,27 @@ the kernel including most fast paths.
returns the slot identifier for the newly registered data type.
.Pp
.Fn osd_set
-returns zero on success or ENOMEM if the specified type/slot identifier pair
+and
+.Fn osd_set_reserved
+return zero on success or ENOMEM if the specified type/slot identifier pair
triggered an internal
.Xr realloc 9
-which failed.
+which failed
+.Fn ( osd_set_reserved
+will always succeed when
+.Fa rsv
+is non-NULL).
.Pp
.Fn osd_get
returns the data pointer for the specified type/slot identifier pair, or NULL
if
the slot has not been initialised yet.
.Pp
+.Fn osd_reserve
+returns a pointer suitable for passing to
+.Fn osd_set_reserved
+or
+.Fn osd_free_reserved .
+.Pp
.Fn osd_call
returns zero if no method is run or the method for each slot runs successfully.
If a method for a slot returns non-zero,
Modified: head/sys/kern/kern_osd.c
==============================================================================
--- head/sys/kern/kern_osd.c Wed Mar 30 16:54:18 2016 (r297421)
+++ head/sys/kern/kern_osd.c Wed Mar 30 16:57:28 2016 (r297422)
@@ -54,7 +54,7 @@ struct osd_master {
struct sx osd_module_lock;
struct rmlock osd_object_lock;
struct mtx osd_list_lock;
- LIST_HEAD(, osd) osd_list; /* (m) */
+ LIST_HEAD(, osd) osd_list; /* (l) */
osd_destructor_t *osd_destructors; /* (o) */
osd_method_t *osd_methods; /* (m) */
u_int osd_ntslots; /* (m) */
@@ -198,6 +198,24 @@ osd_deregister(u_int type, u_int slot)
int
osd_set(u_int type, struct osd *osd, u_int slot, void *value)
{
+
+ return (osd_set_reserved(type, osd, slot, NULL, value));
+}
+
+void *
+osd_reserve(u_int slot)
+{
+
+ KASSERT(slot > 0, ("Invalid slot."));
+
+ OSD_DEBUG("Reserving slot array (slot=%u).", slot);
+ return (malloc(sizeof(void *) * slot, M_OSD, M_WAITOK | M_ZERO));
+}
+
+int
+osd_set_reserved(u_int type, struct osd *osd, u_int slot, void *rsv,
+ void *value)
+{
struct rm_priotracker tracker;
KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
@@ -206,36 +224,34 @@ osd_set(u_int type, struct osd *osd, u_i
rm_rlock(&osdm[type].osd_object_lock, &tracker);
if (slot > osd->osd_nslots) {
+ void *newptr;
+
if (value == NULL) {
OSD_DEBUG(
"Not allocating null slot (type=%u, slot=%u).",
type, slot);
rm_runlock(&osdm[type].osd_object_lock, &tracker);
+ if (rsv)
+ osd_free_reserved(rsv);
return (0);
- } else if (osd->osd_nslots == 0) {
+ }
+
+ /*
+ * Too few slots allocated here, so we need to extend or create
+ * the array.
+ */
+ if (rsv) {
/*
- * First OSD for this object, so we need to allocate
- * space and put it onto the list.
+ * Use the reserve passed in (assumed to be
+ * the right size).
*/
- osd->osd_slots = malloc(sizeof(void *) * slot, M_OSD,
- M_NOWAIT | M_ZERO);
- if (osd->osd_slots == NULL) {
- rm_runlock(&osdm[type].osd_object_lock,
- &tracker);
- return (ENOMEM);
+ newptr = rsv;
+ if (osd->osd_nslots != 0) {
+ memcpy(newptr, osd->osd_slots,
+ sizeof(void *) * osd->osd_nslots);
+ free(osd->osd_slots, M_OSD);
}
- osd->osd_nslots = slot;
- mtx_lock(&osdm[type].osd_list_lock);
- LIST_INSERT_HEAD(&osdm[type].osd_list, osd, osd_next);
- mtx_unlock(&osdm[type].osd_list_lock);
- OSD_DEBUG("Setting first slot (type=%u).", type);
} else {
- void *newptr;
-
- /*
- * Too few slots allocated here, needs to extend
- * the array.
- */
newptr = realloc(osd->osd_slots, sizeof(void *) * slot,
M_OSD, M_NOWAIT | M_ZERO);
if (newptr == NULL) {
@@ -243,11 +259,22 @@ osd_set(u_int type, struct osd *osd, u_i
&tracker);
return (ENOMEM);
}
- osd->osd_slots = newptr;
- osd->osd_nslots = slot;
- OSD_DEBUG("Growing slots array (type=%u).", type);
}
- }
+ if (osd->osd_nslots == 0) {
+ /*
+ * First OSD for this object, so we need to put it
+ * onto the list.
+ */
+ mtx_lock(&osdm[type].osd_list_lock);
+ LIST_INSERT_HEAD(&osdm[type].osd_list, osd, osd_next);
+ mtx_unlock(&osdm[type].osd_list_lock);
+ OSD_DEBUG("Setting first slot (type=%u).", type);
+ } else
+ OSD_DEBUG("Growing slots array (type=%u).", type);
+ osd->osd_slots = newptr;
+ osd->osd_nslots = slot;
+ } else if (rsv)
+ osd_free_reserved(rsv);
OSD_DEBUG("Setting slot value (type=%u, slot=%u, value=%p).", type,
slot, value);
osd->osd_slots[slot - 1] = value;
@@ -255,6 +282,14 @@ osd_set(u_int type, struct osd *osd, u_i
return (0);
}
+void
+osd_free_reserved(void *rsv)
+{
+
+ OSD_DEBUG("Discarding reserved slot array.");
+ free(rsv, M_OSD);
+}
+
void *
osd_get(u_int type, struct osd *osd, u_int slot)
{
Modified: head/sys/sys/osd.h
==============================================================================
--- head/sys/sys/osd.h Wed Mar 30 16:54:18 2016 (r297421)
+++ head/sys/sys/osd.h Wed Mar 30 16:57:28 2016 (r297422)
@@ -59,6 +59,10 @@ int osd_register(u_int type, osd_destruc
void osd_deregister(u_int type, u_int slot);
int osd_set(u_int type, struct osd *osd, u_int slot, void *value);
+void *osd_reserve(u_int slot);
+int osd_set_reserved(u_int type, struct osd *osd, u_int slot, void *rsv,
+ void *value);
+void osd_free_reserved(void *rsv);
void *osd_get(u_int type, struct osd *osd, u_int slot);
void osd_del(u_int type, struct osd *osd, u_int slot);
int osd_call(u_int type, u_int method, void *obj, void *data);
@@ -71,6 +75,8 @@ void osd_exit(u_int type, struct osd *os
osd_deregister(OSD_THREAD, (slot))
#define osd_thread_set(td, slot, value)
\
osd_set(OSD_THREAD, &(td)->td_osd, (slot), (value))
+#define osd_thread_set_reserved(td, slot, rsv, value)
\
+ osd_set_reserved(OSD_THREAD, &(td)->td_osd, (slot), (rsv), (value))
#define osd_thread_get(td, slot)
\
osd_get(OSD_THREAD, &(td)->td_osd, (slot))
#define osd_thread_del(td, slot) do {
\
@@ -88,6 +94,8 @@ void osd_exit(u_int type, struct osd *os
osd_deregister(OSD_JAIL, (slot))
#define osd_jail_set(pr, slot, value)
\
osd_set(OSD_JAIL, &(pr)->pr_osd, (slot), (value))
+#define osd_jail_set_reserved(pr, slot, rsv, value)
\
+ osd_set_reserved(OSD_JAIL, &(pr)->pr_osd, (slot), (rsv), (value))
#define osd_jail_get(pr, slot)
\
osd_get(OSD_JAIL, &(pr)->pr_osd, (slot))
#define osd_jail_del(pr, slot)
\
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