Commit 458e5ff1 authored by Jesper Dangaard Brouer's avatar Jesper Dangaard Brouer Committed by Linus Torvalds
Browse files

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 <hawk@comx.dk>
Signed-off-by: default avatarDoug Thompson <dougthompson@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dd8ef1db

drivers/edac/edac_device.c

+1 −4
Original line number Diff line number Diff line
@@ -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();

}



/*

drivers/edac/edac_mc.c

+1 −3
Original line number Diff line number Diff line
@@ -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();

}



/**

drivers/edac/edac_pci.c

+1 −3
Original line number Diff line number Diff line
@@ -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

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