> -----Original Message-----
> From: Geanta Neag Horia Ioan-B05471
> Sent: Friday, August 31, 2012 6:39 PM
> To: Liu Qiang-B32616; linux-crypto@xxxxxxxxxxxxxxx;
> dan.j.williams@xxxxxxxxx; herbert@xxxxxxxxxxxxxxxxxxxx;
> davem@xxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linuxppc-
> dev@xxxxxxxxxxxxxxxx
> Cc: Li Yang-R58472; Phillips Kim-R1AAHA; vinod.koul@xxxxxxxxx; Dan
> Williams; arnd@xxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx
> Subject: RE: [PATCH v7 1/8] Talitos: Support for async_tx XOR offload
>
> On Fri, 31 Aug 2012 06:08:05 +0300, Liu Qiang-B32616
> <B32616@xxxxxxxxxxxxx>
> wrote:
> > > -----Original Message-----
> > > From: Geanta Neag Horia Ioan-B05471
> > > Sent: Thursday, August 30, 2012 10:23 PM
> > > To: Liu Qiang-B32616; linux-crypto@xxxxxxxxxxxxxxx;
> > > dan.j.williams@xxxxxxxxx; herbert@xxxxxxxxxxxxxxxxxxxx;
> > > davem@xxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linuxppc-
> > > dev@xxxxxxxxxxxxxxxx
> > > Cc: Li Yang-R58472; Phillips Kim-R1AAHA; vinod.koul@xxxxxxxxx;
> > > dan.j.williams@xxxxxxxxx; arnd@xxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx;
> Liu
> > > Qiang-B32616
> > > Subject: RE: [PATCH v7 1/8] Talitos: Support for async_tx XOR offload
> > >
> > > On Thu, 9 Aug 2012 11:20:48 +0300, qiang.liu@xxxxxxxxxxxxx wrote:
> > > > From: Qiang Liu <qiang.liu@xxxxxxxxxxxxx>
> > > >
> > > > Expose Talitos's XOR functionality to be used for RAID parity
> > > > calculation via the Async_tx layer.
> > > >
> > > > Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> > > > Cc: David S. Miller <davem@xxxxxxxxxxxxx>
> > > > Signed-off-by: Dipen Dudhat <Dipen.Dudhat@xxxxxxxxxxxxx>
> > > > Signed-off-by: Maneesh Gupta <Maneesh.Gupta@xxxxxxxxxxxxx>
> > > > Signed-off-by: Kim Phillips <kim.phillips@xxxxxxxxxxxxx>
> > > > Signed-off-by: Vishnu Suresh <Vishnu@xxxxxxxxxxxxx>
> > > > Signed-off-by: Qiang Liu <qiang.liu@xxxxxxxxxxxxx>
> > > > ---
> > > > drivers/crypto/Kconfig | 9 +
> > > > drivers/crypto/talitos.c | 413
> > > ++++++++++++++++++++++++++++++++++++++++++++++
> > > > drivers/crypto/talitos.h | 53 ++++++
> > > > 3 files changed, 475 insertions(+), 0 deletions(-)
> > >
>
> > > > +static int talitos_alloc_chan_resources(struct dma_chan *chan)
> > > > +{
> > > > + struct talitos_xor_chan *xor_chan;
> > > > + struct talitos_xor_desc *desc;
> > > > + LIST_HEAD(tmp_list);
> > > > + int i;
> > > > +
> > > > + xor_chan = container_of(chan, struct talitos_xor_chan,
> common);
> > > > +
> > > > + if (!list_empty(&xor_chan->free_desc))
> > > > + return xor_chan->total_desc;
> > > > +
> > > > + for (i = 0; i < TALITOS_MAX_DESCRIPTOR_NR; i++) {
> > > > + desc = talitos_xor_alloc_descriptor(xor_chan,
> > > > + GFP_KERNEL | GFP_DMA);
> > >
> > > talitos_xor_alloc_descriptor() is called here without holding
> > > the xor_chan->desc_lock and it increments xor_chan->total_desc.
> > > Isn't this an issue ?
> >
> > No, please refer to the code as below,
> > + list_add_tail(&desc->node, &tmp_list);
> >
> > The list is temporary list, it will be merged to xor_chan->free_desc in
> next step, here is protected
> > by lock,
> > + spin_lock_bh(&xor_chan->desc_lock);
> > + list_splice_init(&tmp_list, &xor_chan->free_desc);
> > + spin_unlock_bh(&xor_chan->desc_lock);
>
> I was not referring to the list, but to xor_chan->total_desc variable.
> The following access:
> talitos_alloc_chan_resources()->talitos_xor_alloc_descriptor()-
> >total_desc++
> is not protected by the xor_chan->desc_lock.
Ok, I will correct it in next series. Thanks.
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