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| author | David Howells <dhowells@redhat.com> | 2018-05-23 12:51:29 +0200 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2018-05-23 12:51:29 +0200 |
| commit | 1588def91d58bf70afe1acf9fc0331fa26e974f4 (patch) | |
| tree | d018c9b539d1c789b4dc8bba4c59226a22433a2d /fs | |
| parent | afs: Fix a Sparse warning in xdr_decode_AFSFetchStatus() (diff) | |
| download | linux-1588def91d58bf70afe1acf9fc0331fa26e974f4.tar.xz linux-1588def91d58bf70afe1acf9fc0331fa26e974f4.zip | |
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')
| -rw-r--r-- | fs/afs/cell.c | 8 | ||||
| -rw-r--r-- | fs/afs/internal.h | 2 | ||||
| -rw-r--r-- | fs/afs/proc.c | 2 |
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(); |