[Patch v2] cifs: smbd: Update receive credits before sending and deal with credits roll back on failure before sending

longli
2020-04-02T20:42:13Z

From: Long Li <longli@microsoft.com>

Recevie credits should be updated before sending the packet, not
before a work is scheduled. Also, the value needs roll back if
something fails and cannot send.

Signed-off-by: Long Li <longli@microsoft.com>
Reported-by: kbuild test robot <lkp@intel.com>
---

change in v2: fixed sparse errors reported by kbuild test robot

fs/cifs/smbdirect.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
index c7ef2d7ce0ef..fa52bf3e0236 100644
--- a/fs/cifs/smbdirect.c
+++ b/fs/cifs/smbdirect.c
@@ -450,8 +450,6 @@ static void smbd_post_send_credits(struct work_struct *work)
info->new_credits_offered += ret;
spin_unlock(&info->lock_new_credits_offered);

- atomic_add(ret, &info->receive_credits);
-
/* Check if we can post new receive and grant credits to peer */
check_and_send_immediate(info);
}
@@ -822,6 +820,7 @@ static int smbd_create_header(struct smbd_connection *info,
struct smbd_request *request;
struct smbd_data_transfer *packet;
int header_length;
+ int new_credits;
int rc;

/* Wait for send credits. A SMBD packet needs one credit */
@@ -840,7 +839,7 @@ static int smbd_create_header(struct smbd_connection *info,
request = mempool_alloc(info->request_mempool, GFP_KERNEL);
if (!request) {
rc = -ENOMEM;
- goto err;
+ goto err_alloc;
}

request->info = info;
@@ -848,8 +847,11 @@ static int smbd_create_header(struct smbd_connection *info,
/* Fill in the packet header */
packet = smbd_request_payload(request);
packet->credits_requested = cpu_to_le16(info->send_credit_target);
- packet->credits_granted =
- cpu_to_le16(manage_credits_prior_sending(info));
+
+ new_credits = manage_credits_prior_sending(info);
+ atomic_add(new_credits, &info->receive_credits);
+ packet->credits_granted = cpu_to_le16(new_credits);
+
info->send_immediate = false;

packet->flags = 0;
@@ -887,7 +889,7 @@ static int smbd_create_header(struct smbd_connection *info,
if (ib_dma_mapping_error(info->id->device, request->sge[0].addr)) {
mempool_free(request, info->request_mempool);
rc = -EIO;
- goto err;
+ goto err_dma;
}

request->sge[0].length = header_length;
@@ -896,8 +898,17 @@ static int smbd_create_header(struct smbd_connection *info,
*request_out = request;
return 0;

-err:
+err_dma:
+ /* roll back receive credits */
+ spin_lock(&info->lock_new_credits_offered);
+ info->new_credits_offered += new_credits;
+ spin_unlock(&info->lock_new_credits_offered);
+ atomic_sub(new_credits, &info->receive_credits);
+
+err_alloc:
+ /* roll back send credits */
atomic_inc(&info->send_credits);
+
return rc;
}

--
2.17.1