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authorDavid Howells <dhowells@redhat.com>2018-05-23 11:51:29 +0100
committerDavid Howells <dhowells@redhat.com>2018-05-23 11:51:29 +0100
commit1588def91d58bf70afe1acf9fc0331fa26e974f4 (patch)
treed018c9b539d1c789b4dc8bba4c59226a22433a2d /fs/afs
parentc875c76a061df306ca82b69ba80b8da3ee758c87 (diff)
downloadlinux-1588def91d58bf70afe1acf9fc0331fa26e974f4.tar.bz2
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: f044c8847bb6 ("afs: Lay the groundwork for supporting network namespaces") Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/afs')
-rw-r--r--fs/afs/cell.c8
-rw-r--r--fs/afs/internal.h2
-rw-r--r--fs/afs/proc.c2
3 files changed, 6 insertions, 6 deletions
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index fdf4c36cff79..80fd127239ce 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -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);
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index f8086ec95e24..5d922ad148a8 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -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;
diff --git a/fs/afs/proc.c b/fs/afs/proc.c
index b45ee7576aa8..362f281b1b16 100644
--- a/fs/afs/proc.c
+++ b/fs/afs/proc.c
@@ -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();