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author | Trond Myklebust <Trond.Myklebust@netapp.com> | 2007-07-19 16:32:20 -0400 |
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committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2007-08-07 15:13:16 -0400 |
commit | b247bbf1da69ce376aa1ceb8057331214589e366 (patch) | |
tree | 95451eff3963389d5cb2b93bb74b71f89826bb68 /net | |
parent | 4a2a4df7b6db25df8f3d5cc6dd0b096119359d92 (diff) | |
download | kernel_samsung_smdk4412-b247bbf1da69ce376aa1ceb8057331214589e366.zip kernel_samsung_smdk4412-b247bbf1da69ce376aa1ceb8057331214589e366.tar.gz kernel_samsung_smdk4412-b247bbf1da69ce376aa1ceb8057331214589e366.tar.bz2 |
SUNRPC: Fix a race in rpciod_down()
The commit 4ada539ed77c7a2bbcb75cafbbd7bd8d2b9bef7b lead to the unpleasant
possibility of an asynchronous rpc_task being required to call
rpciod_down() when it is complete. This again means that the rpciod
workqueue may get to call destroy_workqueue on itself -> hang...
Change rpciod_up/rpciod_down to just get/put the module, and then
create/destroy the workqueues on module load/unload.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'net')
-rw-r--r-- | net/sunrpc/sched.c | 57 |
1 files changed, 23 insertions, 34 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index b5723c2..954d7ec 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -50,8 +50,6 @@ static RPC_WAITQ(delay_queue, "delayq"); /* * rpciod-related stuff */ -static DEFINE_MUTEX(rpciod_mutex); -static atomic_t rpciod_users = ATOMIC_INIT(0); struct workqueue_struct *rpciod_workqueue; /* @@ -961,60 +959,49 @@ void rpc_killall_tasks(struct rpc_clnt *clnt) spin_unlock(&clnt->cl_lock); } +int rpciod_up(void) +{ + return try_module_get(THIS_MODULE) ? 0 : -EINVAL; +} + +void rpciod_down(void) +{ + module_put(THIS_MODULE); +} + /* - * Start up the rpciod process if it's not already running. + * Start up the rpciod workqueue. */ -int -rpciod_up(void) +static int rpciod_start(void) { struct workqueue_struct *wq; - int error = 0; - - if (atomic_inc_not_zero(&rpciod_users)) - return 0; - - mutex_lock(&rpciod_mutex); - /* Guard against races with rpciod_down() */ - if (rpciod_workqueue != NULL) - goto out_ok; /* * Create the rpciod thread and wait for it to start. */ dprintk("RPC: creating workqueue rpciod\n"); - error = -ENOMEM; wq = create_workqueue("rpciod"); - if (wq == NULL) - goto out; - rpciod_workqueue = wq; - error = 0; -out_ok: - atomic_inc(&rpciod_users); -out: - mutex_unlock(&rpciod_mutex); - return error; + return rpciod_workqueue != NULL; } -void -rpciod_down(void) +static void rpciod_stop(void) { - if (!atomic_dec_and_test(&rpciod_users)) - return; + struct workqueue_struct *wq = NULL; - mutex_lock(&rpciod_mutex); + if (rpciod_workqueue == NULL) + return; dprintk("RPC: destroying workqueue rpciod\n"); - if (atomic_read(&rpciod_users) == 0 && rpciod_workqueue != NULL) { - destroy_workqueue(rpciod_workqueue); - rpciod_workqueue = NULL; - } - mutex_unlock(&rpciod_mutex); + wq = rpciod_workqueue; + rpciod_workqueue = NULL; + destroy_workqueue(wq); } void rpc_destroy_mempool(void) { + rpciod_stop(); if (rpc_buffer_mempool) mempool_destroy(rpc_buffer_mempool); if (rpc_task_mempool) @@ -1048,6 +1035,8 @@ rpc_init_mempool(void) rpc_buffer_slabp); if (!rpc_buffer_mempool) goto err_nomem; + if (!rpciod_start()) + goto err_nomem; return 0; err_nomem: rpc_destroy_mempool(); |