Re: [PATCH 2/6] target/iscsi: Call .iscsit_release_cmd() once

[Varun Prakash <varun@chelsio.com>]

Hi Nicholas and Bart,

On Sun, Apr 02, 2017 at 03:59:05PM -0700, Nicholas A. Bellinger wrote:
> On Thu, 2017-03-30 at 10:12 -0700, Bart Van Assche wrote:
> > While releasing a command __iscsit_free_cmd() can be called multiple
> > times but .iscsit_release_cmd() must be called only once. Hence move
> > the .iscsit_release_cmd() call into iscsit_release_cmd(). The latter
> > function is only called once per command. The only driver that defines
> > the .iscsit_release_cmd() callback is the cxgbit driver so this change
> > only affects the cxgbit driver.
> > 
> > Fixes: 7ec811a8e9c3 ("iscsi-target: add void (*iscsit_release_cmd)()")
> > Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
> > Cc: Varun Prakash <varun@chelsio.com>
> > Cc: Nicholas Bellinger <nab@linux-iscsi.org>
> > Cc: <stable@vger.kernel.org>
> > ---
> >  drivers/target/iscsi/iscsi_target_util.c | 15 +++++++++------
> >  1 file changed, 9 insertions(+), 6 deletions(-)
> > 
> 
> Applied to target-pending/for-next, but dropping the stable CC' because
> the single caller in cxgbit_release_cmd() is already checking to ensure
> resources are only released on the first invocation.
> 
> So it's not a bug-fix.

In case of DDP cxgbit driver assigns cmd->se_cmd.t_data_sg to ttinfo->sgl
and calls dma_map_sg(), cxgbit_release_cmd() calls dma_unmap_sg(), it needs
a valid sg(ttinfo->sgl), before calling iscsit_release_cmd()
cmd->se_cmd.t_data_sg gets freed so ttinfo->sgl will not be valid if we move
->iscsit_release_cmd() to iscsit_release_cmd().

Thanks
Varun