[Xen-changelog] [linux-2.6.18-xen] xen: netback: save interrupt state in add_to_net_schedule_list_tail

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1284396048 -3600
# Node ID 669c133aef5317183c013c368f36e4c77fb60231
# Parent  0051d294bb60fc096849df586d56a389e32650d4
xen: netback: save interrupt state in add_to_net_schedule_list_tail

add_to_net_schedule_list_tail is called from both hard interrupt
context (add_to_net_schedule_list_tail) and soft interrupt/process
context (netif_schedule_work) so use the interrupt state saving
spinlock variants.

Fixes:
        ------------[ cut here ]------------
        WARNING: at kernel/lockdep.c:2323
        trace_hardirqs_on_caller+0xef/0x1a0()
        Hardware name: PowerEdge 860
        Modules linked in: rtc_cmos rtc_core rtc_lib
        Pid: 16, comm: xenwatch Not tainted
        2.6.32.18-x86_32p-xen0-00850-ge6b9b2c #98
        Call Trace:
         [<c103951c>] warn_slowpath_common+0x6c/0xc0
         [<c1039585>] warn_slowpath_null+0x15/0x20
         [<c105f60f>] trace_hardirqs_on_caller+0xef/0x1a0
         [<c105f6cb>] trace_hardirqs_on+0xb/0x10
         [<c136cc72>] _spin_unlock_irq+0x22/0x40
         [<c11ab9ef>] add_to_net_schedule_list_tail+0x5f/0xb0
         [<c11aba6b>] netif_be_int+0x2b/0x120
         [<c106dd8e>] handle_IRQ_event+0x2e/0xe0
         [<c106f98e>] handle_level_irq+0x6e/0xf0
         [<c1197cdf>] __xen_evtchn_do_upcall+0x16f/0x190
         [<c11981b8>] xen_evtchn_do_upcall+0x28/0x40
         [<c100b487>] xen_do_upcall+0x7/0xc
         [<c119bcf9>] xs_talkv+0x59/0x1a0
         [<c119bf6a>] xs_single+0x3a/0x50
         [<c119c6f9>] xenbus_read+0x39/0x60
         [<c11adf77>] frontend_changed+0x3e7/0x6a0
         [<c119d35a>] xenbus_otherend_changed+0x8a/0xa0
         [<c119d572>] frontend_changed+0x12/0x20
         [<c119b9dc>] xenwatch_thread+0x7c/0x140
         [<c104ea74>] kthread+0x74/0x80
         [<c100b433>] kernel_thread_helper+0x7/0x10
        ---[ end trace 48d73949a8e0909a ]---

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
 drivers/xen/netback/netback.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff -r 0051d294bb60 -r 669c133aef53 drivers/xen/netback/netback.c
--- a/drivers/xen/netback/netback.c     Mon Sep 13 17:39:53 2010 +0100
+++ b/drivers/xen/netback/netback.c     Mon Sep 13 17:40:48 2010 +0100
@@ -821,16 +821,18 @@ static void remove_from_net_schedule_lis
 
 static void add_to_net_schedule_list_tail(netif_t *netif)
 {
+       unsigned long flags;
+
        if (__on_net_schedule_list(netif))
                return;
 
-       spin_lock_irq(&net_schedule_list_lock);
+       spin_lock_irqsave(&net_schedule_list_lock, flags);
        if (!__on_net_schedule_list(netif) &&
            likely(netif_schedulable(netif))) {
                list_add_tail(&netif->list, &net_schedule_list);
                netif_get(netif);
        }
-       spin_unlock_irq(&net_schedule_list_lock);
+       spin_unlock_irqrestore(&net_schedule_list_lock, flags);
 }
 
 /*

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