[PATCH 0/2] introduce QEMU_AUTO_VFREE

[PATCH 0/2] introduce QEMU_AUTO_VFREE

[Vladimir Sementsov-Ogievskiy]

Hi all!

There is a good movement to use g_autofree macro, that helps to
automatically call g_free on exit from code block.

We lack similar possibility for qemu_memalign() functions family. Let's
add, it seems rather simple with help of "cleanup" attribute.

I'll update more places with a follow-up if this is accepted.

Vladimir Sementsov-Ogievskiy (2):
  introduce QEMU_AUTO_VFREE
  block/commit: use QEMU_AUTO_VFREE

 include/qemu/osdep.h |  2 ++
 block/commit.c       | 25 +++++++++----------------
 2 files changed, 11 insertions(+), 16 deletions(-)

-- 
2.29.2

[PATCH 1/2] introduce QEMU_AUTO_VFREE

[Vladimir Sementsov-Ogievskiy]

Introduce a convenient macro, that works for qemu_memalign() like
g_autofree works with g_malloc.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 include/qemu/osdep.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 236a045671..844658a764 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -366,6 +366,8 @@ void *qemu_anon_ram_alloc(size_t size, uint64_t *align, bool shared);
 void qemu_vfree(void *ptr);
 void qemu_anon_ram_free(void *ptr, size_t size);
 
+#define QEMU_AUTO_VFREE __attribute__((cleanup(qemu_vfree)))
+
 #define QEMU_MADV_INVALID -1
 
 #if defined(CONFIG_MADVISE)
-- 
2.29.2

[PATCH 2/2] block/commit: use QEMU_AUTO_VFREE

[Vladimir Sementsov-Ogievskiy]

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/commit.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/block/commit.c b/block/commit.c
index b7f0c7c061..42792b4556 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -119,24 +119,24 @@ static int coroutine_fn commit_run(Job *job, Error **errp)
     uint64_t delay_ns = 0;
     int ret = 0;
     int64_t n = 0; /* bytes */
-    void *buf = NULL;
+    QEMU_AUTO_VFREE void *buf = NULL;
     int64_t len, base_len;
 
-    ret = len = blk_getlength(s->top);
+    len = blk_getlength(s->top);
     if (len < 0) {
-        goto out;
+        return len;
     }
     job_progress_set_remaining(&s->common.job, len);
 
-    ret = base_len = blk_getlength(s->base);
+    base_len = blk_getlength(s->base);
     if (base_len < 0) {
-        goto out;
+        return base_len;
     }
 
     if (base_len < len) {
         ret = blk_truncate(s->base, len, false, PREALLOC_MODE_OFF, 0, NULL);
         if (ret) {
-            goto out;
+            return ret;
         }
     }
 
@@ -174,7 +174,7 @@ static int coroutine_fn commit_run(Job *job, Error **errp)
                 block_job_error_action(&s->common, s->on_error,
                                        error_in_source, -ret);
             if (action == BLOCK_ERROR_ACTION_REPORT) {
-                goto out;
+                return ret;
             } else {
                 n = 0;
                 continue;
@@ -190,12 +190,7 @@ static int coroutine_fn commit_run(Job *job, Error **errp)
         }
     }
 
-    ret = 0;
-
-out:
-    qemu_vfree(buf);
-
-    return ret;
+    return 0;
 }
 
 static const BlockJobDriver commit_job_driver = {
@@ -435,7 +430,7 @@ int bdrv_commit(BlockDriverState *bs)
     int ro;
     int64_t n;
     int ret = 0;
-    uint8_t *buf = NULL;
+    QEMU_AUTO_VFREE uint8_t *buf = NULL;
     Error *local_err = NULL;
 
     if (!drv)
@@ -556,8 +551,6 @@ int bdrv_commit(BlockDriverState *bs)
 
     ret = 0;
 ro_cleanup:
-    qemu_vfree(buf);
-
     blk_unref(backing);
     if (bdrv_cow_bs(bs) != backing_file_bs) {
         bdrv_set_backing_hd(bs, backing_file_bs, &error_abort);
-- 
2.29.2

Re: [PATCH 0/2] introduce QEMU_AUTO_VFREE

[Stefan Hajnoczi]

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On Sat, Jun 19, 2021 at 05:21:18PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Hi all!
> 
> There is a good movement to use g_autofree macro, that helps to
> automatically call g_free on exit from code block.
> 
> We lack similar possibility for qemu_memalign() functions family. Let's
> add, it seems rather simple with help of "cleanup" attribute.
> 
> I'll update more places with a follow-up if this is accepted.
> 
> Vladimir Sementsov-Ogievskiy (2):
>   introduce QEMU_AUTO_VFREE
>   block/commit: use QEMU_AUTO_VFREE
> 
>  include/qemu/osdep.h |  2 ++
>  block/commit.c       | 25 +++++++++----------------
>  2 files changed, 11 insertions(+), 16 deletions(-)
> 
> -- 
> 2.29.2
> 

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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Re: [PATCH 0/2] introduce QEMU_AUTO_VFREE

[Kevin Wolf]

Am 19.06.2021 um 16:21 hat Vladimir Sementsov-Ogievskiy geschrieben:
> Hi all!
> 
> There is a good movement to use g_autofree macro, that helps to
> automatically call g_free on exit from code block.
> 
> We lack similar possibility for qemu_memalign() functions family. Let's
> add, it seems rather simple with help of "cleanup" attribute.
> 
> I'll update more places with a follow-up if this is accepted.

Good idea. Thanks, applied to the block branch.

Kevin

Re: [PATCH 0/2] introduce QEMU_AUTO_VFREE

[Kevin Wolf]

Am 23.06.2021 um 12:34 hat Kevin Wolf geschrieben:
> Am 19.06.2021 um 16:21 hat Vladimir Sementsov-Ogievskiy geschrieben:
> > Hi all!
> > 
> > There is a good movement to use g_autofree macro, that helps to
> > automatically call g_free on exit from code block.
> > 
> > We lack similar possibility for qemu_memalign() functions family. Let's
> > add, it seems rather simple with help of "cleanup" attribute.
> > 
> > I'll update more places with a follow-up if this is accepted.
> 
> Good idea. Thanks, applied to the block branch.

I'm afraid I have to unqueue this:

Failures: 040 141 161 191 249
Failed 5 of 5 iotests

Maybe semantic merge conflicts that I didn't notice while applying or
rebasing.

Kevin

Re: [PATCH 0/2] introduce QEMU_AUTO_VFREE

[Vladimir Sementsov-Ogievskiy]

28.06.2021 13:08, Kevin Wolf wrote:
> Am 23.06.2021 um 12:34 hat Kevin Wolf geschrieben:
>> Am 19.06.2021 um 16:21 hat Vladimir Sementsov-Ogievskiy geschrieben:
>>> Hi all!
>>>
>>> There is a good movement to use g_autofree macro, that helps to
>>> automatically call g_free on exit from code block.
>>>
>>> We lack similar possibility for qemu_memalign() functions family. Let's
>>> add, it seems rather simple with help of "cleanup" attribute.
>>>
>>> I'll update more places with a follow-up if this is accepted.
>>
>> Good idea. Thanks, applied to the block branch.
> 
> I'm afraid I have to unqueue this:
> 
> Failures: 040 141 161 191 249
> Failed 5 of 5 iotests
> 
> Maybe semantic merge conflicts that I didn't notice while applying or
> rebasing.
> 

No, looks like I just made a wrong thing and didn't run tests (hmm, or I was "lucky" and it didn't crash previous time for some reason). I remember, I checked that qemu_vfree is called. But I didn't check the pointer. Now in gdb I see that cleanup function gets pointer to pointer. So we can't reuse qemu_vfree, but need additional function. I'll resend. Sorry for the mess :(


-- 
Best regards,
Vladimir