From 458e5ff13e1bed050990d97e9aa55bcdafc951a7 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Wed, 23 Sep 2009 15:57:29 -0700 Subject: [PATCH] edac: core: remove completion-wait for complete with rcu_barrier Module edac_core.ko uses call_rcu() callbacks in edac_device.c, edac_mc.c and edac_pci.c. They all use a wait_for_completion() scheme, but this scheme it not 100% safe on multiple CPUs. See the _rcu_barrier() implementation which explains why extra precausion is needed. The patch adds a comment about rcu_barrier() and as a precausion calls rcu_barrier(). A maintainer needs to look at removing the wait_for_completion code. [dougthompson@xmission.com: remove the wait_for_completion code] Signed-off-by Jesper Dangaard Brouer Signed-off-by: Doug Thompson Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/edac/edac_device.c | 5 +---- drivers/edac/edac_mc.c | 4 +--- drivers/edac/edac_pci.c | 4 +--- 3 files changed, 3 insertions(+), 10 deletions(-) diff --git a/drivers/edac/edac_device.c b/drivers/edac/edac_device.c index b02a6a69a8f..d5e13c94714 100644 --- a/drivers/edac/edac_device.c +++ b/drivers/edac/edac_device.c @@ -356,7 +356,6 @@ static void complete_edac_device_list_del(struct rcu_head *head) edac_dev = container_of(head, struct edac_device_ctl_info, rcu); INIT_LIST_HEAD(&edac_dev->link); - complete(&edac_dev->removal_complete); } /* @@ -369,10 +368,8 @@ static void del_edac_device_from_global_list(struct edac_device_ctl_info *edac_device) { list_del_rcu(&edac_device->link); - - init_completion(&edac_device->removal_complete); call_rcu(&edac_device->rcu, complete_edac_device_list_del); - wait_for_completion(&edac_device->removal_complete); + rcu_barrier(); } /* diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c index 335b7ebdb11..b629c41756f 100644 --- a/drivers/edac/edac_mc.c +++ b/drivers/edac/edac_mc.c @@ -418,16 +418,14 @@ static void complete_mc_list_del(struct rcu_head *head) mci = container_of(head, struct mem_ctl_info, rcu); INIT_LIST_HEAD(&mci->link); - complete(&mci->complete); } static void del_mc_from_global_list(struct mem_ctl_info *mci) { atomic_dec(&edac_handlers); list_del_rcu(&mci->link); - init_completion(&mci->complete); call_rcu(&mci->rcu, complete_mc_list_del); - wait_for_completion(&mci->complete); + rcu_barrier(); } /** diff --git a/drivers/edac/edac_pci.c b/drivers/edac/edac_pci.c index 30b585b1d60..efb5d565078 100644 --- a/drivers/edac/edac_pci.c +++ b/drivers/edac/edac_pci.c @@ -174,7 +174,6 @@ static void complete_edac_pci_list_del(struct rcu_head *head) pci = container_of(head, struct edac_pci_ctl_info, rcu); INIT_LIST_HEAD(&pci->link); - complete(&pci->complete); } /* @@ -185,9 +184,8 @@ static void complete_edac_pci_list_del(struct rcu_head *head) static void del_edac_pci_from_global_list(struct edac_pci_ctl_info *pci) { list_del_rcu(&pci->link); - init_completion(&pci->complete); call_rcu(&pci->rcu, complete_edac_pci_list_del); - wait_for_completion(&pci->complete); + rcu_barrier(); } #if 0