Re: [PATCH v2 1/1] IB/sa: Put netlink request into the request list before sending

2015-12-10 Thread Doug Ledford 
On 11/13/2015 08:57 AM, Wan, Kaike wrote:
>> From: linux-rdma-ow...@vger.kernel.org [mailto:linux-rdma-
>> ow...@vger.kernel.org] On Behalf Of kaike@intel.com
>> Sent: Friday, October 30, 2015 8:24 AM
>> To: linux-rdma@vger.kernel.org
>> Cc: Wan, Kaike
>> Subject: [PATCH v2 1/1] IB/sa: Put netlink request into the request list 
>> before
>> sending
>>
>> From: Kaike Wan <kaike@intel.com>
>>
>> It was found by Saurabh Sengar that the netlink code tried to allocate
>> memory with GFP_KERNEL while holding a spinlock. While it is possible to fix
>> the issue by replacing GFP_KERNEL with GFP_ATOMIC, it is better to get rid
>> of the spinlock while sending the packet. However, in order to protect
>> against a race condition that a quick response may be received before the
>> request is put on the request list, we need to put the request on the list 
>> first.
>>
>> Signed-off-by: Kaike Wan <kaike@intel.com>
>> ---
> 
> Reported-by: Saurabh Sengar <saurabh.tr...@gmail.com>
> 

This was pulled in for 4.4-rc.  Thanks.


-- 
Doug Ledford <dledf...@redhat.com>
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RE: [PATCH v2 1/1] IB/sa: Put netlink request into the request list before sending

2015-11-13 Thread Wan, Kaike 
> From: linux-rdma-ow...@vger.kernel.org [mailto:linux-rdma-
> ow...@vger.kernel.org] On Behalf Of kaike@intel.com
> Sent: Friday, October 30, 2015 8:24 AM
> To: linux-rdma@vger.kernel.org
> Cc: Wan, Kaike
> Subject: [PATCH v2 1/1] IB/sa: Put netlink request into the request list 
> before
> sending
> 
> From: Kaike Wan <kaike@intel.com>
> 
> It was found by Saurabh Sengar that the netlink code tried to allocate
> memory with GFP_KERNEL while holding a spinlock. While it is possible to fix
> the issue by replacing GFP_KERNEL with GFP_ATOMIC, it is better to get rid
> of the spinlock while sending the packet. However, in order to protect
> against a race condition that a quick response may be received before the
> request is put on the request list, we need to put the request on the list 
> first.
> 
> Signed-off-by: Kaike Wan <kaike@intel.com>
> ---

Reported-by: Saurabh Sengar <saurabh.tr...@gmail.com>

Kaike
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Re: [PATCH v2 1/1] IB/sa: Put netlink request into the request list before sending

2015-10-30 Thread ira.weiny 
On Fri, Oct 30, 2015 at 08:23:45AM -0400, kaike@intel.com wrote:
> From: Kaike Wan 
> 
> It was found by Saurabh Sengar that the netlink code tried to allocate
> memory with GFP_KERNEL while holding a spinlock. While it is possible
> to fix the issue by replacing GFP_KERNEL with GFP_ATOMIC, it is better
> to get rid of the spinlock while sending the packet. However, in order
> to protect against a race condition that a quick response may be received
> before the request is put on the request list, we need to put the request
> on the list first.
> 
> Signed-off-by: Kaike Wan 

Reviewed-by: Ira Weiny 

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[PATCH v2 1/1] IB/sa: Put netlink request into the request list before sending

2015-10-30 Thread kaike . wan 
From: Kaike Wan 

It was found by Saurabh Sengar that the netlink code tried to allocate
memory with GFP_KERNEL while holding a spinlock. While it is possible
to fix the issue by replacing GFP_KERNEL with GFP_ATOMIC, it is better
to get rid of the spinlock while sending the packet. However, in order
to protect against a race condition that a quick response may be received
before the request is put on the request list, we need to put the request
on the list first.

Signed-off-by: Kaike Wan 
---
This patch is based on Doug's k.o/for-4.4 branch

Changes since v1:
-- Pass gfp_mask to ib_nl_send_msg for internal memory allocation, as suggested
   by Ira Weiny;
-- Queue the netlink timeout work before the request is sent to avoid potential
   race condition where the query is freed by the response handler.

 drivers/infiniband/core/sa_query.c |   32 +---
 1 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/drivers/infiniband/core/sa_query.c 
b/drivers/infiniband/core/sa_query.c
index dcdaa79..1495c00 100644
--- a/drivers/infiniband/core/sa_query.c
+++ b/drivers/infiniband/core/sa_query.c
@@ -512,7 +512,7 @@ static int ib_nl_get_path_rec_attrs_len(ib_sa_comp_mask 
comp_mask)
return len;
 }
 
-static int ib_nl_send_msg(struct ib_sa_query *query)
+static int ib_nl_send_msg(struct ib_sa_query *query, gfp_t gfp_mask)
 {
struct sk_buff *skb = NULL;
struct nlmsghdr *nlh;
@@ -526,7 +526,7 @@ static int ib_nl_send_msg(struct ib_sa_query *query)
if (len <= 0)
return -EMSGSIZE;
 
-   skb = nlmsg_new(len, GFP_KERNEL);
+   skb = nlmsg_new(len, gfp_mask);
if (!skb)
return -ENOMEM;
 
@@ -544,7 +544,7 @@ static int ib_nl_send_msg(struct ib_sa_query *query)
/* Repair the nlmsg header length */
nlmsg_end(skb, nlh);
 
-   ret = ibnl_multicast(skb, nlh, RDMA_NL_GROUP_LS, GFP_KERNEL);
+   ret = ibnl_multicast(skb, nlh, RDMA_NL_GROUP_LS, gfp_mask);
if (!ret)
ret = len;
else
@@ -553,7 +553,7 @@ static int ib_nl_send_msg(struct ib_sa_query *query)
return ret;
 }
 
-static int ib_nl_make_request(struct ib_sa_query *query)
+static int ib_nl_make_request(struct ib_sa_query *query, gfp_t gfp_mask)
 {
unsigned long flags;
unsigned long delay;
@@ -562,25 +562,27 @@ static int ib_nl_make_request(struct ib_sa_query *query)
INIT_LIST_HEAD(>list);
query->seq = (u32)atomic_inc_return(_nl_sa_request_seq);
 
+   /* Put the request on the list first.*/
spin_lock_irqsave(_nl_request_lock, flags);
-   ret = ib_nl_send_msg(query);
-   if (ret <= 0) {
-   ret = -EIO;
-   goto request_out;
-   } else {
-   ret = 0;
-   }
-
delay = msecs_to_jiffies(sa_local_svc_timeout_ms);
query->timeout = delay + jiffies;
list_add_tail(>list, _nl_request_list);
/* Start the timeout if this is the only request */
if (ib_nl_request_list.next == >list)
queue_delayed_work(ib_nl_wq, _nl_timed_work, delay);
-
-request_out:
spin_unlock_irqrestore(_nl_request_lock, flags);
 
+   ret = ib_nl_send_msg(query, gfp_mask);
+   if (ret <= 0) {
+   ret = -EIO;
+   /* Remove the request */
+   spin_lock_irqsave(_nl_request_lock, flags);
+   list_del(>list);
+   spin_unlock_irqrestore(_nl_request_lock, flags);
+   } else {
+   ret = 0;
+   }
+
return ret;
 }
 
@@ -1108,7 +1110,7 @@ static int send_mad(struct ib_sa_query *query, int 
timeout_ms, gfp_t gfp_mask)
 
if (query->flags & IB_SA_ENABLE_LOCAL_SERVICE) {
if (!ibnl_chk_listeners(RDMA_NL_GROUP_LS)) {
-   if (!ib_nl_make_request(query))
+   if (!ib_nl_make_request(query, gfp_mask))
return id;
}
ib_sa_disable_local_svc(query);
-- 
1.7.1

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Re: [PATCH v2 1/1] IB/sa: Put netlink request into the request list before sending

2015-10-30 Thread Jason Gunthorpe 
On Fri, Oct 30, 2015 at 08:23:45AM -0400, kaike@intel.com wrote:
> From: Kaike Wan 
> 
> It was found by Saurabh Sengar that the netlink code tried to allocate
> memory with GFP_KERNEL while holding a spinlock. While it is possible
> to fix the issue by replacing GFP_KERNEL with GFP_ATOMIC, it is better
> to get rid of the spinlock while sending the packet. However, in order
> to protect against a race condition that a quick response may be received
> before the request is put on the request list, we need to put the request
> on the list first.
> 
> Signed-off-by: Kaike Wan 

Reviewed-by: Jason Gunthorpe 

Jason
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