Messages in this thread Patch in this message | | | Date | Wed, 26 Aug 2009 14:45:32 -0600 | From | dougthompson@xmission ... | Subject | [PATCH 1/1] edac: core remove completion-wait for complete with rcu_barrier |
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From: Jesper Dangaard Brouer <hawk@comx.dk>
Module edac_core.ko uses call_rcu() callbacks in edac_device.c, edac_mc.c and edac_pci.c.
They all uses 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.
Maintainer Doug Thompson removed the wait_for_completion code
Signed-off-by Jesper Dangaard Brouer" <hawk@comx.dk> Signed-off-by: Doug Thompson <dougthompson@xmission.com> ---
Index: linux-2.6.31-rc7/drivers/edac/edac_device.c =================================================================== --- linux-2.6.31-rc7.orig/drivers/edac/edac_device.c 2009-08-21 19:00:46.000000000 -0600 +++ linux-2.6.31-rc7/drivers/edac/edac_device.c 2009-08-26 14:39:00.000000000 -0600 @@ -356,7 +356,6 @@ static void complete_edac_device_list_de 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_ *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(); } /* Index: linux-2.6.31-rc7/drivers/edac/edac_mc.c =================================================================== --- linux-2.6.31-rc7.orig/drivers/edac/edac_mc.c 2009-08-21 19:00:46.000000000 -0600 +++ linux-2.6.31-rc7/drivers/edac/edac_mc.c 2009-08-26 14:35:35.000000000 -0600 @@ -418,16 +418,14 @@ static void complete_mc_list_del(struct 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(); } /** Index: linux-2.6.31-rc7/drivers/edac/edac_pci.c =================================================================== --- linux-2.6.31-rc7.orig/drivers/edac/edac_pci.c 2009-08-21 19:00:46.000000000 -0600 +++ linux-2.6.31-rc7/drivers/edac/edac_pci.c 2009-08-26 14:36:31.000000000 -0600 @@ -174,7 +174,6 @@ static void complete_edac_pci_list_del(s 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(s 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
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