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Subject[PATCH 02/20] afs: Fix checker warnings
From
Date
Fix warnings raised by checker, including:

(*) Warnings raised by unequal comparison for the purposes of sorting,
where the endianness doesn't matter:

fs/afs/addr_list.c:246:21: warning: restricted __be16 degrades to integer
fs/afs/addr_list.c:246:30: warning: restricted __be16 degrades to integer
fs/afs/addr_list.c:248:21: warning: restricted __be32 degrades to integer
fs/afs/addr_list.c:248:49: warning: restricted __be32 degrades to integer
fs/afs/addr_list.c:283:21: warning: restricted __be16 degrades to integer
fs/afs/addr_list.c:283:30: warning: restricted __be16 degrades to integer

(*) afs_set_cb_interest() is not actually used and can be removed.

(*) afs_cell_gc_delay() should be provided with a sysctl.

(*) afs_cell_destroy() needs to use rcu_access_pointer() to read
cell->vl_addrs.

(*) afs_init_fs_cursor() should be static.

(*) struct afs_vnode::permit_cache needs to be marked __rcu.

(*) afs_server_rcu() needs to use rcu_access_pointer().

(*) afs_destroy_server() should use rcu_access_pointer() on
server->addresses as the server object is no longer accessible.

(*) afs_find_server() casts __be16/__be32 values to int in order to
directly compare them for the purpose of finding a match in a list,
but is should also annotate the cast with __force to avoid checker
warnings.

(*) afs_check_permit() accesses vnode->permit_cache outside of the RCU
readlock, though it doesn't then access the value; the extraneous
access is deleted.

False positives:

(*) Conditional locking around the code in xdr_decode_AFSFetchStatus. This
can be dealt with in a separate patch.

fs/afs/fsclient.c:148:9: warning: context imbalance in 'xdr_decode_AFSFetchStatus' - different lock contexts for basic block

(*) Incorrect handling of seq-retry lock context balance:

fs/afs/inode.c:455:38: warning: context imbalance in 'afs_getattr' - different
lock contexts for basic block
fs/afs/server.c:52:17: warning: context imbalance in 'afs_find_server' - different lock contexts for basic block
fs/afs/server.c:128:17: warning: context imbalance in 'afs_find_server_by_uuid' - different lock contexts for basic block

Errors:

(*) afs_lookup_cell_rcu() needs to break out of the seq-retry loop, not go
round again if it successfully found the workstation cell.

(*) Fix UUID decode in afs_deliver_cb_probe_uuid().

(*) afs_cache_permit() has a missing rcu_read_unlock() before one of the
jumps to the someone_else_changed_it label. Move the unlock to after
the label.

(*) afs_vl_get_addrs_u() is using ntohl() rather than htonl() when
encoding to XDR.

(*) afs_deliver_yfsvl_get_endpoints() is using htonl() rather than ntohl()
when decoding from XDR.

Signed-off-by: David Howells <dhowells@redhat.com>
---

fs/afs/addr_list.c | 6 +++---
fs/afs/callback.c | 20 --------------------
fs/afs/cell.c | 6 +++---
fs/afs/cmservice.c | 6 +++---
fs/afs/inode.c | 2 +-
fs/afs/internal.h | 2 +-
fs/afs/proc.c | 8 ++++++++
fs/afs/rotate.c | 2 +-
fs/afs/security.c | 11 +++--------
fs/afs/server.c | 14 ++++++++------
fs/afs/vlclient.c | 8 ++++----
11 files changed, 35 insertions(+), 50 deletions(-)

diff --git a/fs/afs/addr_list.c b/fs/afs/addr_list.c
index fd9f28b8a933..3bedfed608a2 100644
--- a/fs/afs/addr_list.c
+++ b/fs/afs/addr_list.c
@@ -243,9 +243,9 @@ void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port)
xport == a->sin6_port)
return;
if (xdr == a->sin6_addr.s6_addr32[3] &&
- xport < a->sin6_port)
+ (u16 __force)xport < (u16 __force)a->sin6_port)
break;
- if (xdr < a->sin6_addr.s6_addr32[3])
+ if ((u32 __force)xdr < (u32 __force)a->sin6_addr.s6_addr32[3])
break;
}

@@ -280,7 +280,7 @@ void afs_merge_fs_addr6(struct afs_addr_list *alist, __be32 *xdr, u16 port)
xport == a->sin6_port)
return;
if (diff == 0 &&
- xport < a->sin6_port)
+ (u16 __force)xport < (u16 __force)a->sin6_port)
break;
if (diff < 0)
break;
diff --git a/fs/afs/callback.c b/fs/afs/callback.c
index f4291b576054..bf082c719645 100644
--- a/fs/afs/callback.c
+++ b/fs/afs/callback.c
@@ -96,26 +96,6 @@ int afs_register_server_cb_interest(struct afs_vnode *vnode,
return 0;
}

-/*
- * Set a vnode's interest on a server.
- */
-void afs_set_cb_interest(struct afs_vnode *vnode, struct afs_cb_interest *cbi)
-{
- struct afs_cb_interest *old_cbi = NULL;
-
- if (vnode->cb_interest == cbi)
- return;
-
- write_seqlock(&vnode->cb_lock);
- if (vnode->cb_interest != cbi) {
- afs_get_cb_interest(cbi);
- old_cbi = vnode->cb_interest;
- vnode->cb_interest = cbi;
- }
- write_sequnlock(&vnode->cb_lock);
- afs_put_cb_interest(afs_v2net(vnode), cbi);
-}
-
/*
* Remove an interest on a server.
*/
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index 4235a05afc76..69b95faacc5e 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -18,7 +18,7 @@
#include <keys/rxrpc-type.h>
#include "internal.h"

-unsigned __read_mostly afs_cell_gc_delay = 10;
+static unsigned __read_mostly afs_cell_gc_delay = 10;

static void afs_manage_cell(struct work_struct *);

@@ -75,7 +75,7 @@ struct afs_cell *afs_lookup_cell_rcu(struct afs_net *net,
cell = rcu_dereference_raw(net->ws_cell);
if (cell) {
afs_get_cell(cell);
- continue;
+ break;
}
ret = -EDESTADDRREQ;
continue;
@@ -411,7 +411,7 @@ static void afs_cell_destroy(struct rcu_head *rcu)

ASSERTCMP(atomic_read(&cell->usage), ==, 0);

- afs_put_addrlist(cell->vl_addrs);
+ afs_put_addrlist(rcu_access_pointer(cell->vl_addrs));
key_put(cell->anonymous_key);
kfree(cell);

diff --git a/fs/afs/cmservice.c b/fs/afs/cmservice.c
index 41e277f57b20..83ff283979a4 100644
--- a/fs/afs/cmservice.c
+++ b/fs/afs/cmservice.c
@@ -500,9 +500,9 @@ static int afs_deliver_cb_probe_uuid(struct afs_call *call)

b = call->buffer;
r = call->request;
- r->time_low = ntohl(b[0]);
- r->time_mid = ntohl(b[1]);
- r->time_hi_and_version = ntohl(b[2]);
+ r->time_low = b[0];
+ r->time_mid = htons(ntohl(b[1]));
+ r->time_hi_and_version = htons(ntohl(b[2]));
r->clock_seq_hi_and_reserved = ntohl(b[3]);
r->clock_seq_low = ntohl(b[4]);

diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 65c5b1edd338..d5db9dead18c 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -544,7 +544,7 @@ void afs_evict_inode(struct inode *inode)
}
#endif

- afs_put_permits(vnode->permit_cache);
+ afs_put_permits(rcu_access_pointer(vnode->permit_cache));
_leave("");
}

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index a6a1d75eee41..135192b7dc04 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -458,7 +458,7 @@ struct afs_vnode {
#ifdef CONFIG_AFS_FSCACHE
struct fscache_cookie *cache; /* caching cookie */
#endif
- struct afs_permits *permit_cache; /* cache of permits so far obtained */
+ struct afs_permits __rcu *permit_cache; /* cache of permits so far obtained */
struct mutex io_lock; /* Lock for serialising I/O on this mutex */
struct mutex validate_lock; /* lock for validating this vnode */
spinlock_t wb_lock; /* lock for wb_keys */
diff --git a/fs/afs/proc.c b/fs/afs/proc.c
index 4508dd54f789..1c95756335b7 100644
--- a/fs/afs/proc.c
+++ b/fs/afs/proc.c
@@ -183,6 +183,7 @@ static int afs_proc_cells_open(struct inode *inode, struct file *file)
* first item
*/
static void *afs_proc_cells_start(struct seq_file *m, loff_t *_pos)
+ __acquires(rcu)
{
struct afs_net *net = afs_seq2net(m);

@@ -204,6 +205,7 @@ static void *afs_proc_cells_next(struct seq_file *m, void *v, loff_t *pos)
* clean up after reading from the cells list
*/
static void afs_proc_cells_stop(struct seq_file *m, void *v)
+ __releases(rcu)
{
rcu_read_unlock();
}
@@ -413,6 +415,7 @@ static int afs_proc_cell_volumes_open(struct inode *inode, struct file *file)
* first item
*/
static void *afs_proc_cell_volumes_start(struct seq_file *m, loff_t *_pos)
+ __acquires(cell->proc_lock)
{
struct afs_cell *cell = m->private;

@@ -438,6 +441,7 @@ static void *afs_proc_cell_volumes_next(struct seq_file *p, void *v,
* clean up after reading from the cells list
*/
static void afs_proc_cell_volumes_stop(struct seq_file *p, void *v)
+ __releases(cell->proc_lock)
{
struct afs_cell *cell = p->private;

@@ -500,6 +504,7 @@ static int afs_proc_cell_vlservers_open(struct inode *inode, struct file *file)
* first item
*/
static void *afs_proc_cell_vlservers_start(struct seq_file *m, loff_t *_pos)
+ __acquires(rcu)
{
struct afs_addr_list *alist;
struct afs_cell *cell = m->private;
@@ -544,6 +549,7 @@ static void *afs_proc_cell_vlservers_next(struct seq_file *p, void *v,
* clean up after reading from the cells list
*/
static void afs_proc_cell_vlservers_stop(struct seq_file *p, void *v)
+ __releases(rcu)
{
rcu_read_unlock();
}
@@ -580,6 +586,7 @@ static int afs_proc_servers_open(struct inode *inode, struct file *file)
* first item.
*/
static void *afs_proc_servers_start(struct seq_file *m, loff_t *_pos)
+ __acquires(rcu)
{
struct afs_net *net = afs_seq2net(m);

@@ -601,6 +608,7 @@ static void *afs_proc_servers_next(struct seq_file *m, void *v, loff_t *_pos)
* clean up after reading from the cells list
*/
static void afs_proc_servers_stop(struct seq_file *p, void *v)
+ __releases(rcu)
{
rcu_read_unlock();
}
diff --git a/fs/afs/rotate.c b/fs/afs/rotate.c
index ad1328d85526..ac0feac9d746 100644
--- a/fs/afs/rotate.c
+++ b/fs/afs/rotate.c
@@ -21,7 +21,7 @@
/*
* Initialise a filesystem server cursor for iterating over FS servers.
*/
-void afs_init_fs_cursor(struct afs_fs_cursor *fc, struct afs_vnode *vnode)
+static void afs_init_fs_cursor(struct afs_fs_cursor *fc, struct afs_vnode *vnode)
{
memset(fc, 0, sizeof(*fc));
}
diff --git a/fs/afs/security.c b/fs/afs/security.c
index b88b7d45fdaa..bd82c5bf4a6a 100644
--- a/fs/afs/security.c
+++ b/fs/afs/security.c
@@ -178,18 +178,14 @@ void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
}
}

- if (cb_break != (vnode->cb_break + vnode->cb_interest->server->cb_s_break)) {
- rcu_read_unlock();
+ if (cb_break != (vnode->cb_break + vnode->cb_interest->server->cb_s_break))
goto someone_else_changed_it;
- }

/* We need a ref on any permits list we want to copy as we'll have to
* drop the lock to do memory allocation.
*/
- if (permits && !refcount_inc_not_zero(&permits->usage)) {
- rcu_read_unlock();
+ if (permits && !refcount_inc_not_zero(&permits->usage))
goto someone_else_changed_it;
- }

rcu_read_unlock();

@@ -278,6 +274,7 @@ void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
/* Someone else changed the cache under us - don't recheck at this
* time.
*/
+ rcu_read_unlock();
return;
}

@@ -296,8 +293,6 @@ int afs_check_permit(struct afs_vnode *vnode, struct key *key,
_enter("{%x:%u},%x",
vnode->fid.vid, vnode->fid.vnode, key_serial(key));

- permits = vnode->permit_cache;
-
/* check the permits to see if we've got one yet */
if (key == vnode->volume->cell->anonymous_key) {
_debug("anon");
diff --git a/fs/afs/server.c b/fs/afs/server.c
index a43ef77dabae..e23be63998a8 100644
--- a/fs/afs/server.c
+++ b/fs/afs/server.c
@@ -59,7 +59,8 @@ struct afs_server *afs_find_server(struct afs_net *net,
alist = rcu_dereference(server->addresses);
for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
b = &alist->addrs[i].transport.sin6;
- diff = (u16)a->sin6_port - (u16)b->sin6_port;
+ diff = ((u16 __force)a->sin6_port -
+ (u16 __force)b->sin6_port);
if (diff == 0)
diff = memcmp(&a->sin6_addr,
&b->sin6_addr,
@@ -79,10 +80,11 @@ struct afs_server *afs_find_server(struct afs_net *net,
alist = rcu_dereference(server->addresses);
for (i = 0; i < alist->nr_ipv4; i++) {
b = &alist->addrs[i].transport.sin6;
- diff = (u16)a->sin6_port - (u16)b->sin6_port;
+ diff = ((u16 __force)a->sin6_port -
+ (u16 __force)b->sin6_port);
if (diff == 0)
- diff = ((u32)a->sin6_addr.s6_addr32[3] -
- (u32)b->sin6_addr.s6_addr32[3]);
+ diff = ((u32 __force)a->sin6_addr.s6_addr32[3] -
+ (u32 __force)b->sin6_addr.s6_addr32[3]);
if (diff == 0)
goto found;
if (diff < 0) {
@@ -381,7 +383,7 @@ static void afs_server_rcu(struct rcu_head *rcu)
{
struct afs_server *server = container_of(rcu, struct afs_server, rcu);

- afs_put_addrlist(server->addresses);
+ afs_put_addrlist(rcu_access_pointer(server->addresses));
kfree(server);
}

@@ -390,7 +392,7 @@ static void afs_server_rcu(struct rcu_head *rcu)
*/
static void afs_destroy_server(struct afs_net *net, struct afs_server *server)
{
- struct afs_addr_list *alist = server->addresses;
+ struct afs_addr_list *alist = rcu_access_pointer(server->addresses);
struct afs_addr_cursor ac = {
.alist = alist,
.addr = &alist->addrs[0],
diff --git a/fs/afs/vlclient.c b/fs/afs/vlclient.c
index 5d8562f1ad4a..f9d89795e41b 100644
--- a/fs/afs/vlclient.c
+++ b/fs/afs/vlclient.c
@@ -303,7 +303,7 @@ struct afs_addr_list *afs_vl_get_addrs_u(struct afs_net *net,
r->uuid.clock_seq_hi_and_reserved = htonl(u->clock_seq_hi_and_reserved);
r->uuid.clock_seq_low = htonl(u->clock_seq_low);
for (i = 0; i < 6; i++)
- r->uuid.node[i] = ntohl(u->node[i]);
+ r->uuid.node[i] = htonl(u->node[i]);

trace_afs_make_vl_call(call);
return (struct afs_addr_list *)afs_make_call(ac, call, GFP_KERNEL, false);
@@ -504,7 +504,7 @@ static int afs_deliver_yfsvl_get_endpoints(struct afs_call *call)
/* Got either the type of the next entry or the count of
* volEndpoints if no more fsEndpoints.
*/
- call->count2 = htonl(*bp++);
+ call->count2 = ntohl(*bp++);

call->offset = 0;
call->count--;
@@ -531,7 +531,7 @@ static int afs_deliver_yfsvl_get_endpoints(struct afs_call *call)
return ret;

bp = call->buffer;
- call->count2 = htonl(*bp++);
+ call->count2 = ntohl(*bp++);
call->offset = 0;
call->unmarshall = 4;

@@ -576,7 +576,7 @@ static int afs_deliver_yfsvl_get_endpoints(struct afs_call *call)
call->offset = 0;
call->count--;
if (call->count > 0) {
- call->count2 = htonl(*bp++);
+ call->count2 = ntohl(*bp++);
goto again;
}

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