[3.8.y.z extended stable] Patch "net: rds: fix per-cpu helper usage" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    net: rds: fix per-cpu helper usage

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.17.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From fd8368c31e1007b06e87da7049700172ba085023 Mon Sep 17 00:00:00 2001
From: Gerald Schaefer <gerald.schaefer at de.ibm.com>
Date: Thu, 16 Jan 2014 16:54:48 +0100
Subject: net: rds: fix per-cpu helper usage

commit c196403b79aa241c3fefb3ee5bb328aa7c5cc860 upstream.

commit ae4b46e9d "net: rds: use this_cpu_* per-cpu helper" broke per-cpu
handling for rds. chpfirst is the result of __this_cpu_read(), so it is
an absolute pointer and not __percpu. Therefore, __this_cpu_write()
should not operate on chpfirst, but rather on cache->percpu->first, just
like __this_cpu_read() did before.

Signed-off-byd Gerald Schaefer <gerald.schaefer at de.ibm.com>

Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/rds/ib_recv.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 8eb9501..b7ebe23 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -421,8 +421,7 @@ static void rds_ib_recv_cache_put(struct list_head *new_item,
 				 struct rds_ib_refill_cache *cache)
 {
 	unsigned long flags;
-	struct list_head *old;
-	struct list_head __percpu *chpfirst;
+	struct list_head *old, *chpfirst;

 	local_irq_save(flags);

@@ -432,7 +431,7 @@ static void rds_ib_recv_cache_put(struct list_head *new_item,
 	else /* put on front */
 		list_add_tail(new_item, chpfirst);

-	__this_cpu_write(chpfirst, new_item);
+	__this_cpu_write(cache->percpu->first, new_item);
 	__this_cpu_inc(cache->percpu->count);

 	if (__this_cpu_read(cache->percpu->count) < RDS_IB_RECYCLE_BATCH_COUNT)
@@ -452,7 +451,7 @@ static void rds_ib_recv_cache_put(struct list_head *new_item,
 	} while (old);


-	__this_cpu_write(chpfirst, NULL);
+	__this_cpu_write(cache->percpu->first, NULL);
 	__this_cpu_write(cache->percpu->count, 0);
 end:
 	local_irq_restore(flags);
--
1.8.3.2