On Fri, 31 Aug 2012 06:08:05 +0300, Liu Qiang-B32616 [off-list ref]
wrote:
quoted
-----Original Message-----
From: Geanta Neag Horia Ioan-B05471
Sent: Thursday, August 30, 2012 10:23 PM
To: Liu Qiang-B32616; <redacted>;
dan.j.williams@gmail.com; herbert@gondor.hengli.com.au;
davem@davemloft.net; linux-kernel@vger.kernel.org; linuxppc-
dev@lists.ozlabs.org
Cc: Li Yang-R58472; Phillips Kim-R1AAHA; <redacted>;
dan.j.williams@intel.com; arnd@arndb.de; gregkh@linuxfoundation.org; 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@freescale.com wrote:
quoted
From: Qiang Liu <redacted>
Expose Talitos's XOR functionality to be used for RAID parity
calculation via the Async_tx layer.
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Dipen Dudhat <redacted>
Signed-off-by: Maneesh Gupta <redacted>
Signed-off-by: Kim Phillips <redacted>
Signed-off-by: Vishnu Suresh <redacted>
Signed-off-by: Qiang Liu <redacted>
---
drivers/crypto/Kconfig | 9 +
drivers/crypto/talitos.c | 413
++++++++++++++++++++++++++++++++++++++++++++++
quoted
drivers/crypto/talitos.h | 53 ++++++
3 files changed, 475 insertions(+), 0 deletions(-)
quoted
quoted
+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.