agp(4): release unbinded memory
While experimenting with the agp(4) interface I found that if you
release the interface (AGPIOC_RELEASE) before closing its file
descriptor you'll end up with allocated but unbinded memory blocks.
This behavior is due to the fact that the agp_release_helper() function
doesn't free the memory associated to each block and this is incoherent
with what it says it does:
/*
* Clear out the aperture and free any
* outstanding memory blocks.
*/
...
So the diff below correct this by freeing all the memory block when
releasing the interface, this is what happens currently if you close
the file descriptor without releasing the interface.
However it doesn't change the behavior of the interface that looks
busted to me because we don't keep track of who allocated some memory
block and end up unbindind and freeing everything.
Ok?
Index: agp.c
===
RCS file: /cvs/src/sys/dev/pci/agp.c,v
retrieving revision 1.34
diff -u -p -r1.34 agp.c
--- agp.c 26 Dec 2010 15:41:00 - 1.34
+++ agp.c 12 Nov 2012 18:20:48 -
@@ -290,20 +310,13 @@ int
agpclose(dev_t dev, int flags, int devtype, struct proc *p)
{
struct agp_softc *sc = agp_find_device(AGPUNIT(dev));
- struct agp_memory *mem;
/*
* Clear the GATT and force release on last close
*/
- if (sc-sc_state == AGP_ACQUIRE_USER) {
- while ((mem = TAILQ_FIRST(sc-sc_memory)) != 0) {
- if (mem-am_is_bound) {
- agp_unbind_memory(sc, mem);
- }
- agp_free_memory(sc, mem);
- }
+ if (sc-sc_state == AGP_ACQUIRE_USER)
agp_release_helper(sc, AGP_ACQUIRE_USER);
- }
+
sc-sc_opened = 0;
return (0);
@@ -658,25 +671,26 @@ int
agp_release_helper(void *dev, enum agp_acquire_state state)
{
struct agp_softc *sc = (struct agp_softc *)dev;
- struct agp_memory* mem;
+ struct agp_memory *mem, *tmp;
if (sc-sc_state == AGP_ACQUIRE_FREE)
return (0);
- if (sc-sc_state != state)
+ if (sc-sc_state != state)
return (EBUSY);
/*
* Clear out the aperture and free any
* outstanding memory blocks.
*/
- TAILQ_FOREACH(mem, sc-sc_memory, am_link) {
+ TAILQ_FOREACH_SAFE(mem, sc-sc_memory, am_link, tmp) {
if (mem-am_is_bound) {
- printf(agp_release_helper: mem %d is bound\n,
- mem-am_id);
+ AGP_DPF(mem %d is bound\n, mem-am_id);
agp_unbind_memory(sc, mem);
}
+ agp_free_memory(sc, mem);
}
+
sc-sc_state = AGP_ACQUIRE_FREE;
return (0);
}
Re: agp(4): release unbinded memory
Date: Tue, 13 Nov 2012 12:30:29 +0100 From: Martin Pieuchot mpieuc...@nolizard.org While experimenting with the agp(4) interface I found that if you release the interface (AGPIOC_RELEASE) before closing its file descriptor you'll end up with allocated but unbinded memory blocks. That behaviour is documented in agp(4). So if we change it, we should change the documentation as well. That said, the documentation also says that the AGPIOC_RELEASE ioctl doesn't unbind any allocated memory. And that doesn't seem to be true. This behavior is due to the fact that the agp_release_helper() function doesn't free the memory associated to each block and this is incoherent with what it says it does: /* * Clear out the aperture and free any * outstanding memory blocks. */ ... So the diff below correct this by freeing all the memory block when releasing the interface, this is what happens currently if you close the file descriptor without releasing the interface. I;m not sure this is right. I think the idea here is that an application could release control to hand things over to drm, and later reacquire control. The comment in xenocara/xserver/hw/xfree86/os-support/bsd/bsd_agp.c:xf86ReleaseGART() suggests that this behaviour is desired.
Re: agp(4): release unbinded memory
On 13/11/12(Tue) 13:45, Mark Kettenis wrote:
Date: Tue, 13 Nov 2012 12:30:29 +0100
From: Martin Pieuchot mpieuc...@nolizard.org
While experimenting with the agp(4) interface I found that if you
release the interface (AGPIOC_RELEASE) before closing its file
descriptor you'll end up with allocated but unbinded memory blocks.
That behaviour is documented in agp(4). So if we change it, we should
change the documentation as well. That said, the documentation also
says that the AGPIOC_RELEASE ioctl doesn't unbind any allocated
memory. And that doesn't seem to be true.
This behavior is due to the fact that the agp_release_helper() function
doesn't free the memory associated to each block and this is incoherent
with what it says it does:
/*
* Clear out the aperture and free any
* outstanding memory blocks.
*/
...
So the diff below correct this by freeing all the memory block when
releasing the interface, this is what happens currently if you close
the file descriptor without releasing the interface.
I;m not sure this is right. I think the idea here is that an
application could release control to hand things over to drm, and
later reacquire control. The comment in
xenocara/xserver/hw/xfree86/os-support/bsd/bsd_agp.c:xf86ReleaseGART()
suggests that this behaviour is desired.
Fair enough, so here's a diff that removes the chunk of code unbinding
the memory block from the release routine. This makes the code match
what the manual says.
Ok?
Index: agp.c
===
RCS file: /cvs/src/sys/dev/pci/agp.c,v
retrieving revision 1.34
diff -u -p -r1.34 agp.c
--- agp.c 26 Dec 2010 15:41:00 - 1.34
+++ agp.c 13 Nov 2012 13:41:43 -
@@ -658,25 +678,13 @@ int
agp_release_helper(void *dev, enum agp_acquire_state state)
{
struct agp_softc *sc = (struct agp_softc *)dev;
- struct agp_memory* mem;
if (sc-sc_state == AGP_ACQUIRE_FREE)
return (0);
- if (sc-sc_state != state)
+ if (sc-sc_state != state)
return (EBUSY);
- /*
-* Clear out the aperture and free any
-* outstanding memory blocks.
-*/
- TAILQ_FOREACH(mem, sc-sc_memory, am_link) {
- if (mem-am_is_bound) {
- printf(agp_release_helper: mem %d is bound\n,
- mem-am_id);
- agp_unbind_memory(sc, mem);
- }
- }
sc-sc_state = AGP_ACQUIRE_FREE;
return (0);
}
Re: agp(4): release unbinded memory
Date: Tue, 13 Nov 2012 16:15:59 +0100
From: Martin Pieuchot mpieuc...@nolizard.org
On 13/11/12(Tue) 13:45, Mark Kettenis wrote:
Date: Tue, 13 Nov 2012 12:30:29 +0100
From: Martin Pieuchot mpieuc...@nolizard.org
While experimenting with the agp(4) interface I found that if you
release the interface (AGPIOC_RELEASE) before closing its file
descriptor you'll end up with allocated but unbinded memory blocks.
That behaviour is documented in agp(4). So if we change it, we should
change the documentation as well. That said, the documentation also
says that the AGPIOC_RELEASE ioctl doesn't unbind any allocated
memory. And that doesn't seem to be true.
This behavior is due to the fact that the agp_release_helper() function
doesn't free the memory associated to each block and this is incoherent
with what it says it does:
/*
* Clear out the aperture and free any
* outstanding memory blocks.
*/
...
So the diff below correct this by freeing all the memory block when
releasing the interface, this is what happens currently if you close
the file descriptor without releasing the interface.
I;m not sure this is right. I think the idea here is that an
application could release control to hand things over to drm, and
later reacquire control. The comment in
xenocara/xserver/hw/xfree86/os-support/bsd/bsd_agp.c:xf86ReleaseGART()
suggests that this behaviour is desired.
Fair enough, so here's a diff that removes the chunk of code unbinding
the memory block from the release routine. This makes the code match
what the manual says.
Ok?
Hmm, I think it currently pretty much a bug if a process calls
AGPIOC_RELEASE while it still has stuff bound to the aperture as we
don't restore the bindings when we resume. So I think we should keep
the printf's and perhaps keep unbinding the memory as well. I'm not
sure how much damage stale mappings can do during a suspend/resume
cycle.
It seems that the xf86-video-intel driver is the only userland code
that actually uses /dev/agp (through the xserver interfaces). And
because of the FreeBSD hack I mentioned in my previous mail, I don't
think it actually ever invokes the AGPIOC_RELEASE ioctl after it
starts using the GART. It's a great bloody mess :(. But fortunately
that usage goes away as soon as we implement KMS.
Index: agp.c
===
RCS file: /cvs/src/sys/dev/pci/agp.c,v
retrieving revision 1.34
diff -u -p -r1.34 agp.c
--- agp.c 26 Dec 2010 15:41:00 - 1.34
+++ agp.c 13 Nov 2012 13:41:43 -
@@ -658,25 +678,13 @@ int
agp_release_helper(void *dev, enum agp_acquire_state state)
{
struct agp_softc *sc = (struct agp_softc *)dev;
- struct agp_memory* mem;
if (sc-sc_state == AGP_ACQUIRE_FREE)
return (0);
- if (sc-sc_state != state)
+ if (sc-sc_state != state)
return (EBUSY);
- /*
- * Clear out the aperture and free any
- * outstanding memory blocks.
- */
- TAILQ_FOREACH(mem, sc-sc_memory, am_link) {
- if (mem-am_is_bound) {
- printf(agp_release_helper: mem %d is bound\n,
- mem-am_id);
- agp_unbind_memory(sc, mem);
- }
- }
sc-sc_state = AGP_ACQUIRE_FREE;
return (0);
}
