Message ID | 20200701015859.29820-1-alxndr@bu.edu (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | pc: fix leak in pc_system_flash_cleanup_unused | expand |
On 01/07/20 03:58, Alexander Bulekov wrote: > fix a leak detected when building with --enable-sanitizers: > ./i386-softmmu/qemu-system-i386 > Upon exit: > ==13576==ERROR: LeakSanitizer: detected memory leaks > > Direct leak of 1216 byte(s) in 1 object(s) allocated from: > #0 0x7f9d2ed5c628 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.5) > #1 0x7f9d2e963500 in g_malloc (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.) > #2 0x55fa646d25cc in object_new_with_type /tmp/qemu/qom/object.c:686 > #3 0x55fa63dbaa88 in qdev_new /tmp/qemu/hw/core/qdev.c:140 > #4 0x55fa638a533f in pc_pflash_create /tmp/qemu/hw/i386/pc_sysfw.c:88 > #5 0x55fa638a54c4 in pc_system_flash_create /tmp/qemu/hw/i386/pc_sysfw.c:106 > #6 0x55fa646caa1d in object_init_with_type /tmp/qemu/qom/object.c:369 > #7 0x55fa646d20b5 in object_initialize_with_type /tmp/qemu/qom/object.c:511 > #8 0x55fa646d2606 in object_new_with_type /tmp/qemu/qom/object.c:687 > #9 0x55fa639431e9 in qemu_init /tmp/qemu/softmmu/vl.c:3878 > #10 0x55fa6335c1b8 in main /tmp/qemu/softmmu/main.c:48 > #11 0x7f9d2cf06e0a in __libc_start_main ../csu/libc-start.c:308 > #12 0x55fa6335f8e9 in _start (/tmp/qemu/build/i386-softmmu/qemu-system-i386) > > Signed-off-by: Alexander Bulekov <alxndr@bu.edu> > --- > > I am not very familiar with the QOM, so maybe this isn't the right way > of going about this. With the call to object_property_add_child in > pc_sysfw.c:pc_pflash_create, object_ref is called on the pflash device. > In the pc_system_flash_cleanup_unused function, there are calls to > object_propery_del and object_unparent, but it seems neither of these > calls object_unref. So do we need to manually decrement the refcount? Yes; you can also add it in pc_pflash_create, because /* * Since object_property_add_child added a reference to the child object, * we can drop the reference added by object_initialize(), so the child * property will own the only reference to the object. */ (from object_initialize_childv). Paolo > hw/i386/pc_sysfw.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c > index ec2a3b3e7e..f69a93671a 100644 > --- a/hw/i386/pc_sysfw.c > +++ b/hw/i386/pc_sysfw.c > @@ -123,6 +123,7 @@ static void pc_system_flash_cleanup_unused(PCMachineState *pcms) > object_property_del(OBJECT(pcms), prop_name); > g_free(prop_name); > object_unparent(dev_obj); > + object_unref(dev_obj); > pcms->flash[i] = NULL; > } > } >
On 7/1/20 3:58 AM, Alexander Bulekov wrote: > fix a leak detected when building with --enable-sanitizers: > ./i386-softmmu/qemu-system-i386 > Upon exit: > ==13576==ERROR: LeakSanitizer: detected memory leaks > > Direct leak of 1216 byte(s) in 1 object(s) allocated from: > #0 0x7f9d2ed5c628 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.5) > #1 0x7f9d2e963500 in g_malloc (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.) > #2 0x55fa646d25cc in object_new_with_type /tmp/qemu/qom/object.c:686 > #3 0x55fa63dbaa88 in qdev_new /tmp/qemu/hw/core/qdev.c:140 > #4 0x55fa638a533f in pc_pflash_create /tmp/qemu/hw/i386/pc_sysfw.c:88 > #5 0x55fa638a54c4 in pc_system_flash_create /tmp/qemu/hw/i386/pc_sysfw.c:106 > #6 0x55fa646caa1d in object_init_with_type /tmp/qemu/qom/object.c:369 > #7 0x55fa646d20b5 in object_initialize_with_type /tmp/qemu/qom/object.c:511 > #8 0x55fa646d2606 in object_new_with_type /tmp/qemu/qom/object.c:687 > #9 0x55fa639431e9 in qemu_init /tmp/qemu/softmmu/vl.c:3878 > #10 0x55fa6335c1b8 in main /tmp/qemu/softmmu/main.c:48 > #11 0x7f9d2cf06e0a in __libc_start_main ../csu/libc-start.c:308 > #12 0x55fa6335f8e9 in _start (/tmp/qemu/build/i386-softmmu/qemu-system-i386) > > Signed-off-by: Alexander Bulekov <alxndr@bu.edu> > --- > > I am not very familiar with the QOM, so maybe this isn't the right way > of going about this. With the call to object_property_add_child in > pc_sysfw.c:pc_pflash_create, object_ref is called on the pflash device. > In the pc_system_flash_cleanup_unused function, there are calls to > object_propery_del and object_unparent, but it seems neither of these > calls object_unref. So do we need to manually decrement the refcount? Hint in such case, look at who wrote the commit, and Cc the author to get an explanation: $ git blame hw/i386/pc_sysfw.c ebc29e1beab hw/i386/pc_sysfw.c (Markus Armbruster 2019-03-11 18:39:26 +0100 119) for (i = 0; i < ARRAY_SIZE(pcms->flash); i++) { ebc29e1beab hw/i386/pc_sysfw.c (Markus Armbruster 2019-03-11 18:39:26 +0100 120) dev_obj = OBJECT(pcms->flash[i]); ebc29e1beab hw/i386/pc_sysfw.c (Markus Armbruster 2019-03-11 18:39:26 +0100 121) if (!object_property_get_bool(dev_obj, "realized", &error_abort)) { ebc29e1beab hw/i386/pc_sysfw.c (Markus Armbruster 2019-03-11 18:39:26 +0100 122) prop_name = g_strdup_printf("pflash%d", i); df4fe0b291b hw/i386/pc_sysfw.c (Markus Armbruster 2020-05-05 17:29:26 +0200 123) object_property_del(OBJECT(pcms), prop_name); ebc29e1beab hw/i386/pc_sysfw.c (Markus Armbruster 2019-03-11 18:39:26 +0100 124) g_free(prop_name); ebc29e1beab hw/i386/pc_sysfw.c (Markus Armbruster 2019-03-11 18:39:26 +0100 125) object_unparent(dev_obj); ebc29e1beab hw/i386/pc_sysfw.c (Markus Armbruster 2019-03-11 18:39:26 +0100 126) pcms->flash[i] = NULL; ebc29e1beab hw/i386/pc_sysfw.c (Markus Armbruster 2019-03-11 18:39:26 +0100 127) } ebc29e1beab hw/i386/pc_sysfw.c (Markus Armbruster 2019-03-11 18:39:26 +0100 128) } > > hw/i386/pc_sysfw.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c > index ec2a3b3e7e..f69a93671a 100644 > --- a/hw/i386/pc_sysfw.c > +++ b/hw/i386/pc_sysfw.c > @@ -123,6 +123,7 @@ static void pc_system_flash_cleanup_unused(PCMachineState *pcms) > object_property_del(OBJECT(pcms), prop_name); > g_free(prop_name); > object_unparent(dev_obj); > + object_unref(dev_obj); > pcms->flash[i] = NULL; > } > } >
On 200701 0749, Paolo Bonzini wrote: > On 01/07/20 03:58, Alexander Bulekov wrote: > > fix a leak detected when building with --enable-sanitizers: > > ./i386-softmmu/qemu-system-i386 > > Upon exit: > > ==13576==ERROR: LeakSanitizer: detected memory leaks > > > > Direct leak of 1216 byte(s) in 1 object(s) allocated from: > > #0 0x7f9d2ed5c628 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.5) > > #1 0x7f9d2e963500 in g_malloc (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.) > > #2 0x55fa646d25cc in object_new_with_type /tmp/qemu/qom/object.c:686 > > #3 0x55fa63dbaa88 in qdev_new /tmp/qemu/hw/core/qdev.c:140 > > #4 0x55fa638a533f in pc_pflash_create /tmp/qemu/hw/i386/pc_sysfw.c:88 > > #5 0x55fa638a54c4 in pc_system_flash_create /tmp/qemu/hw/i386/pc_sysfw.c:106 > > #6 0x55fa646caa1d in object_init_with_type /tmp/qemu/qom/object.c:369 > > #7 0x55fa646d20b5 in object_initialize_with_type /tmp/qemu/qom/object.c:511 > > #8 0x55fa646d2606 in object_new_with_type /tmp/qemu/qom/object.c:687 > > #9 0x55fa639431e9 in qemu_init /tmp/qemu/softmmu/vl.c:3878 > > #10 0x55fa6335c1b8 in main /tmp/qemu/softmmu/main.c:48 > > #11 0x7f9d2cf06e0a in __libc_start_main ../csu/libc-start.c:308 > > #12 0x55fa6335f8e9 in _start (/tmp/qemu/build/i386-softmmu/qemu-system-i386) > > > > Signed-off-by: Alexander Bulekov <alxndr@bu.edu> > > --- > > > > I am not very familiar with the QOM, so maybe this isn't the right way > > of going about this. With the call to object_property_add_child in > > pc_sysfw.c:pc_pflash_create, object_ref is called on the pflash device. > > In the pc_system_flash_cleanup_unused function, there are calls to > > object_propery_del and object_unparent, but it seems neither of these > > calls object_unref. So do we need to manually decrement the refcount? > > Yes; you can also add it in pc_pflash_create, because > > /* > * Since object_property_add_child added a reference to the child object, > * we can drop the reference added by object_initialize(), so the child > * property will own the only reference to the object. > */ > > (from object_initialize_childv). Isn't that reference used at pc_sysfw.c:104 ? pcms->flash[0] = pc_pflash_create(pcms, "system.flash0", "pflash0"); In this case, shouldn't we unref when pc_sysfw.c:126 pcms->flash[0] = NULL ? -Alex > Paolo > > > hw/i386/pc_sysfw.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c > > index ec2a3b3e7e..f69a93671a 100644 > > --- a/hw/i386/pc_sysfw.c > > +++ b/hw/i386/pc_sysfw.c > > @@ -123,6 +123,7 @@ static void pc_system_flash_cleanup_unused(PCMachineState *pcms) > > object_property_del(OBJECT(pcms), prop_name); > > g_free(prop_name); > > object_unparent(dev_obj); > > + object_unref(dev_obj); > > pcms->flash[i] = NULL; > > } > > } > > >
On 01/07/20 15:06, Alexander Bulekov wrote: >> Yes; you can also add it in pc_pflash_create, because >> >> /* >> * Since object_property_add_child added a reference to the child object, >> * we can drop the reference added by object_initialize(), so the child >> * property will own the only reference to the object. >> */ >> >> (from object_initialize_childv). > Isn't that reference used at pc_sysfw.c:104 ? > pcms->flash[0] = pc_pflash_create(pcms, "system.flash0", "pflash0"); > > In this case, shouldn't we unref when > pc_sysfw.c:126 pcms->flash[0] = NULL > ? object_unparent already drops a reference. Therefore, it's okay to drop the reference immediately after object_property_add_child (which adds a reference) and match pc_pflash_create with just object_unparent. Paolo
diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c index ec2a3b3e7e..f69a93671a 100644 --- a/hw/i386/pc_sysfw.c +++ b/hw/i386/pc_sysfw.c @@ -123,6 +123,7 @@ static void pc_system_flash_cleanup_unused(PCMachineState *pcms) object_property_del(OBJECT(pcms), prop_name); g_free(prop_name); object_unparent(dev_obj); + object_unref(dev_obj); pcms->flash[i] = NULL; } }
fix a leak detected when building with --enable-sanitizers: ./i386-softmmu/qemu-system-i386 Upon exit: ==13576==ERROR: LeakSanitizer: detected memory leaks Direct leak of 1216 byte(s) in 1 object(s) allocated from: #0 0x7f9d2ed5c628 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.5) #1 0x7f9d2e963500 in g_malloc (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.) #2 0x55fa646d25cc in object_new_with_type /tmp/qemu/qom/object.c:686 #3 0x55fa63dbaa88 in qdev_new /tmp/qemu/hw/core/qdev.c:140 #4 0x55fa638a533f in pc_pflash_create /tmp/qemu/hw/i386/pc_sysfw.c:88 #5 0x55fa638a54c4 in pc_system_flash_create /tmp/qemu/hw/i386/pc_sysfw.c:106 #6 0x55fa646caa1d in object_init_with_type /tmp/qemu/qom/object.c:369 #7 0x55fa646d20b5 in object_initialize_with_type /tmp/qemu/qom/object.c:511 #8 0x55fa646d2606 in object_new_with_type /tmp/qemu/qom/object.c:687 #9 0x55fa639431e9 in qemu_init /tmp/qemu/softmmu/vl.c:3878 #10 0x55fa6335c1b8 in main /tmp/qemu/softmmu/main.c:48 #11 0x7f9d2cf06e0a in __libc_start_main ../csu/libc-start.c:308 #12 0x55fa6335f8e9 in _start (/tmp/qemu/build/i386-softmmu/qemu-system-i386) Signed-off-by: Alexander Bulekov <alxndr@bu.edu> --- I am not very familiar with the QOM, so maybe this isn't the right way of going about this. With the call to object_property_add_child in pc_sysfw.c:pc_pflash_create, object_ref is called on the pflash device. In the pc_system_flash_cleanup_unused function, there are calls to object_propery_del and object_unparent, but it seems neither of these calls object_unref. So do we need to manually decrement the refcount? hw/i386/pc_sysfw.c | 1 + 1 file changed, 1 insertion(+)