[PULL 0/1] vfio-ccw: another bugfix

[PULL 0/1] vfio-ccw: another bugfix

[Cornelia Huck]

The following changes since commit 6cf09958f32b9667bb3ebadf74367c791112771b:

  s390: correct module section names for expoline code revert (2018-04-23 07:57:17 +0200)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/vfio-ccw.git tags/vfio-ccw-20180424

for you to fetch changes up to 427e522fc72395a4571b8dd7fe6d116927496bf7:

  vfio: ccw: fix cleanup if cp_prefetch fails (2018-04-23 14:11:20 +0200)

----------------------------------------------------------------
Another vfio-ccw bug fix: Don't clean up things on error that were
never translated in the first place.

----------------------------------------------------------------

Halil Pasic (1):
  vfio: ccw: fix cleanup if cp_prefetch fails

 drivers/s390/cio/vfio_ccw_cp.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

-- 
2.14.3

[PULL 1/1] vfio: ccw: fix cleanup if cp_prefetch fails

[Cornelia Huck]

From: Halil Pasic <pasic@linux.vnet.ibm.com>

If the translation of a channel program fails, we may end up attempting
to clean up (free, unpin) stuff that never got translated (and allocated,
pinned) in the first place.

By adjusting the lengths of the chains accordingly (so the element that
failed, and all subsequent elements are excluded) cleanup activities
based on false assumptions can be avoided.

Let's make sure cp_free works properly after cp_prefetch returns with an
error by setting ch_len of a ccw chain to the number of the translated
CCWs on that chain.

Cc: stable@vger.kernel.org #v4.12+
Acked-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Reviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20180423110113.59385-2-bjsdjshi@linux.vnet.ibm.com>
[CH: fixed typos]
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---
 drivers/s390/cio/vfio_ccw_cp.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index 2c7550797ec2..dce92b2a895d 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -715,6 +715,10 @@ void cp_free(struct channel_program *cp)
  * and stores the result to ccwchain list. @cp must have been
  * initialized by a previous call with cp_init(). Otherwise, undefined
  * behavior occurs.
+ * For each chain composing the channel program:
+ * - On entry ch_len holds the count of CCWs to be translated.
+ * - On exit ch_len is adjusted to the count of successfully translated CCWs.
+ * This allows cp_free to find in ch_len the count of CCWs to free in a chain.
  *
  * The S/390 CCW Translation APIS (prefixed by 'cp_') are introduced
  * as helpers to do ccw chain translation inside the kernel. Basically
@@ -749,11 +753,18 @@ int cp_prefetch(struct channel_program *cp)
 		for (idx = 0; idx < len; idx++) {
 			ret = ccwchain_fetch_one(chain, idx, cp);
 			if (ret)
-				return ret;
+				goto out_err;
 		}
 	}
 
 	return 0;
+out_err:
+	/* Only cleanup the chain elements that were actually translated. */
+	chain->ch_len = idx;
+	list_for_each_entry_continue(chain, &cp->ccwchain_list, next) {
+		chain->ch_len = 0;
+	}
+	return ret;
 }
 
 /**
-- 
2.14.3

Re: [PULL 0/1] vfio-ccw: another bugfix

[Martin Schwidefsky]

On Tue, 24 Apr 2018 13:26:55 +0200
Cornelia Huck <cohuck@redhat.com> wrote:

> The following changes since commit 6cf09958f32b9667bb3ebadf74367c791112771b:
> 
>   s390: correct module section names for expoline code revert (2018-04-23 07:57:17 +0200)
> 
> are available in the Git repository at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/vfio-ccw.git tags/vfio-ccw-20180424
> 
> for you to fetch changes up to 427e522fc72395a4571b8dd7fe6d116927496bf7:
> 
>   vfio: ccw: fix cleanup if cp_prefetch fails (2018-04-23 14:11:20 +0200)
> 
> ----------------------------------------------------------------
> Another vfio-ccw bug fix: Don't clean up things on error that were
> never translated in the first place.
> 
> ----------------------------------------------------------------
> 
> Halil Pasic (1):
>   vfio: ccw: fix cleanup if cp_prefetch fails
> 
>  drivers/s390/cio/vfio_ccw_cp.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 

Now added the s390/linux:fixes. Thanks.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.