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Commit 1588def9 authored by David Howells's avatar David Howells
Browse files

afs: Mark afs_net::ws_cell as __rcu and set using rcu functions 



The afs_net::ws_cell member is sometimes used under RCU conditions from
within an seq-readlock.  It isn't, however, marked __rcu and it isn't set
using the proper RCU barrier-imposing functions.

Fix this by annotating it with __rcu and using appropriate barriers to
make sure accesses are correctly ordered.

Without this, the code can produce the following warning:

>> fs/afs/proc.c:151:24: sparse: incompatible types in comparison expression (different address spaces)

Fixes: f044c884 ("afs: Lay the groundwork for supporting network namespaces")
Reported-by: default avatarkbuild test robot <lkp@intel.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent c875c76a

fs/afs/cell.c

+4 −4
Original line number Diff line number Diff line
@@ -341,8 +341,8 @@ int afs_cell_init(struct afs_net *net, const char *rootcell) 


	/* install the new cell */

	write_seqlock(&net->cells_lock);

	old_root = net->ws_cell;

	net->ws_cell = new_root;

	old_root = rcu_access_pointer(net->ws_cell);

	rcu_assign_pointer(net->ws_cell, new_root);

	write_sequnlock(&net->cells_lock);



	afs_put_cell(net, old_root);
@@ -755,8 +755,8 @@ void afs_cell_purge(struct afs_net *net) 
	_enter("");



	write_seqlock(&net->cells_lock);

	ws = net->ws_cell;

	net->ws_cell = NULL;

	ws = rcu_access_pointer(net->ws_cell);

	RCU_INIT_POINTER(net->ws_cell, NULL);

	write_sequnlock(&net->cells_lock);

	afs_put_cell(net, ws);

fs/afs/internal.h

+1 −1
Original line number Diff line number Diff line
@@ -231,7 +231,7 @@ struct afs_net { 


	/* Cell database */

	struct rb_root		cells;

	struct afs_cell		*ws_cell;

	struct afs_cell __rcu	*ws_cell;

	struct work_struct	cells_manager;

	struct timer_list	cells_timer;

	atomic_t		cells_outstanding;

fs/afs/proc.c

+1 −1
Original line number Diff line number Diff line
@@ -173,7 +173,7 @@ static ssize_t afs_proc_rootcell_read(struct file *file, char __user *buf, 


	if (*_pos > 0)

		return 0;

	if (!net->ws_cell)

	if (!rcu_access_pointer(net->ws_cell))

		return 0;



	rcu_read_lock();