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edac: core: remove completion-wait for complete with rcu_barrier

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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 <hawk@comx.dk>
Signed-off-by: Doug Thompson <dougthompson@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jesper Dangaard Brouer 2009-09-23 15:57:29 -07:00 committed by Linus Torvalds
parent dd8ef1db87
commit 458e5ff13e
3 changed files with 3 additions and 10 deletions
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5
drivers/edac/edac_device.c
View file

@ -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();
}
/*

4
drivers/edac/edac_mc.c
View file

@ -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();
}
/**

4
drivers/edac/edac_pci.c
View file

@ -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