On Fri, 6 Jun 2008 14:11:16 -0400
Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> On Fri, 6 Jun 2008 13:24:31 -0400
> "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote:
>
...
> > How does the module refcounting work after this patch?
> >
> > --b.
> >
>
> I think I've goofed this part, actually. I was thinking that we didn't
> need to bump the refcount here, and that the kernel would realize that
> nfsd() hadn't returned and would prevent unloading until it had. This
> doesn't seem to be the case. I'll need to go back and add refcounting
> back in.
>
Here's a respun patch that adds back in the module refcounts and also
removes the unneeded "err = 0;" at the bottom of the loop. Thoughts?
-----------[snip]--------------
>From 794f3137ec5a5a8720b091f00b22807dab8f1be2 Mon Sep 17 00:00:00 2001
From: Jeff Layton <jlayton@xxxxxxxxxx>
Date: Fri, 6 Jun 2008 14:44:23 -0400
Subject: [PATCH 4/5] knfsd: convert knfsd to kthread API
This patch is rather large, but I couldn't figure out a way to break it
up that would remain bisectable. It does several things:
- change svc_thread_fn typedef to better match what kthread_create expects
- change svc_pool_map_set_cpumask to be more kthread friendly. Make it
take a task arg and and get rid of the "oldmask"
- have svc_set_num_threads call kthread_create directly
- eliminate __svc_create_thread
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/nfsd/nfssvc.c | 49 +++++++++++++--------
include/linux/sunrpc/svc.h | 2 +-
net/sunrpc/svc.c | 102 +++++++++++++++-----------------------------
3 files changed, 66 insertions(+), 87 deletions(-)
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 6339cb7..7fdfa23 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -21,6 +21,7 @@
#include <linux/smp_lock.h>
#include <linux/freezer.h>
#include <linux/fs_struct.h>
+#include <linux/kthread.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/stats.h>
@@ -46,7 +47,7 @@
#define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGHUP) | sigmask(SIGINT) | sigmask(SIGQUIT))
extern struct svc_program nfsd_program;
-static void nfsd(struct svc_rqst *rqstp);
+static int nfsd(void *vrqstp);
struct timeval nfssvc_boot;
static atomic_t nfsd_busy;
static unsigned long nfsd_last_call;
@@ -407,18 +408,20 @@ update_thread_usage(int busy_threads)
/*
* This is the NFS server kernel thread
*/
-static void
-nfsd(struct svc_rqst *rqstp)
+static int
+nfsd(void *vrqstp)
{
+ struct svc_rqst *rqstp = (struct svc_rqst *) vrqstp;
struct fs_struct *fsp;
- int err;
sigset_t shutdown_mask, allowed_mask;
+ int err, preverr = 0;
+ unsigned int signo;
/* Lock module and set up kernel thread */
+ __module_get(THIS_MODULE);
mutex_lock(&nfsd_mutex);
- daemonize("nfsd");
- /* After daemonize() this kernel thread shares current->fs
+ /* At this point, the thread shares current->fs
* with the init process. We need to create files with a
* umask of 0 instead of init's umask. */
fsp = copy_fs_struct(current->fs);
@@ -433,14 +436,18 @@ nfsd(struct svc_rqst *rqstp)
siginitsetinv(&shutdown_mask, SHUTDOWN_SIGS);
siginitsetinv(&allowed_mask, ALLOWED_SIGS);
+ /*
+ * thread is spawned with all signals set to SIG_IGN, re-enable
+ * the ones that matter
+ */
+ for (signo = 1; signo <= _NSIG; signo++) {
+ if (!sigismember(&shutdown_mask, signo))
+ allow_signal(signo);
+ }
nfsdstats.th_cnt++;
-
- rqstp->rq_task = current;
-
mutex_unlock(&nfsd_mutex);
-
/*
* We want less throttling in balance_dirty_pages() so that nfs to
* localhost doesn't cause nfsd to lock up due to all the client's
@@ -462,15 +469,25 @@ nfsd(struct svc_rqst *rqstp)
*/
while ((err = svc_recv(rqstp, 60*60*HZ)) == -EAGAIN)
;
- if (err < 0)
+ if (err == -EINTR)
break;
+ else if (err < 0) {
+ if (err != preverr) {
+ printk(KERN_WARNING "%s: unexpected error "
+ "from svc_recv (%d)\n", __func__, -err);
+ preverr = err;
+ }
+ schedule_timeout_uninterruptible(HZ);
+ continue;
+ }
+
update_thread_usage(atomic_read(&nfsd_busy));
atomic_inc(&nfsd_busy);
/* Lock the export hash tables for reading. */
exp_readlock();
- /* Process request with signals blocked. */
+ /* Process request with signals blocked. */
sigprocmask(SIG_SETMASK, &allowed_mask, NULL);
svc_process(rqstp);
@@ -481,23 +498,19 @@ nfsd(struct svc_rqst *rqstp)
atomic_dec(&nfsd_busy);
}
- if (err != -EINTR)
- printk(KERN_WARNING "nfsd: terminating on error %d\n", -err);
-
/* Clear signals before calling svc_exit_thread() */
flush_signals(current);
mutex_lock(&nfsd_mutex);
-
nfsdstats.th_cnt --;
out:
/* Release the thread */
svc_exit_thread(rqstp);
-
- /* Release module */
mutex_unlock(&nfsd_mutex);
+
module_put_and_exit(0);
+ return 0;
}
static __be32 map_new_errors(u32 vers, __be32 nfserr)
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 4b54c5f..011d6d8 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -22,7 +22,7 @@
/*
* This is the RPC server thread function prototype
*/
-typedef void (*svc_thread_fn)(struct svc_rqst *);
+typedef int (*svc_thread_fn)(void *);
/*
*
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 7bffaff..f461da2 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -18,6 +18,7 @@
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/module.h>
+#include <linux/kthread.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/xdr.h>
@@ -291,15 +292,14 @@ svc_pool_map_put(void)
/*
- * Set the current thread's cpus_allowed mask so that it
+ * Set the given thread's cpus_allowed mask so that it
* will only run on cpus in the given pool.
- *
- * Returns 1 and fills in oldmask iff a cpumask was applied.
*/
-static inline int
-svc_pool_map_set_cpumask(unsigned int pidx, cpumask_t *oldmask)
+static inline void
+svc_pool_map_set_cpumask(struct task_struct *task, unsigned int pidx)
{
struct svc_pool_map *m = &svc_pool_map;
+ unsigned int node = m->pool_to[pidx];
/*
* The caller checks for sv_nrpools > 1, which
@@ -307,26 +307,17 @@ svc_pool_map_set_cpumask(unsigned int pidx, cpumask_t *oldmask)
*/
BUG_ON(m->count == 0);
- switch (m->mode)
- {
- default:
- return 0;
+ switch (m->mode) {
case SVC_POOL_PERCPU:
{
- unsigned int cpu = m->pool_to[pidx];
-
- *oldmask = current->cpus_allowed;
- set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
- return 1;
+ set_cpus_allowed_ptr(task, &cpumask_of_cpu(node));
+ break;
}
case SVC_POOL_PERNODE:
{
- unsigned int node = m->pool_to[pidx];
node_to_cpumask_ptr(nodecpumask, node);
-
- *oldmask = current->cpus_allowed;
- set_cpus_allowed_ptr(current, nodecpumask);
- return 1;
+ set_cpus_allowed_ptr(task, nodecpumask);
+ break;
}
}
}
@@ -579,47 +570,6 @@ out_enomem:
EXPORT_SYMBOL(svc_prepare_thread);
/*
- * Create a thread in the given pool. Caller must hold BKL or another lock to
- * serialize access to the svc_serv struct. On a NUMA or SMP machine, with a
- * multi-pool serv, the thread will be restricted to run on the cpus belonging
- * to the pool.
- */
-static int
-__svc_create_thread(svc_thread_fn func, struct svc_serv *serv,
- struct svc_pool *pool)
-{
- struct svc_rqst *rqstp;
- int error = -ENOMEM;
- int have_oldmask = 0;
- cpumask_t uninitialized_var(oldmask);
-
- rqstp = svc_prepare_thread(serv, pool);
- if (IS_ERR(rqstp)) {
- error = PTR_ERR(rqstp);
- goto out;
- }
-
- if (serv->sv_nrpools > 1)
- have_oldmask = svc_pool_map_set_cpumask(pool->sp_id, &oldmask);
-
- error = kernel_thread((int (*)(void *)) func, rqstp, 0);
-
- if (have_oldmask)
- set_cpus_allowed(current, oldmask);
-
- if (error < 0)
- goto out_thread;
- svc_sock_update_bufs(serv);
- error = 0;
-out:
- return error;
-
-out_thread:
- svc_exit_thread(rqstp);
- goto out;
-}
-
-/*
* Choose a pool in which to create a new thread, for svc_set_num_threads
*/
static inline struct svc_pool *
@@ -688,7 +638,9 @@ found_pool:
int
svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{
- struct task_struct *victim;
+ struct svc_rqst *rqstp;
+ struct task_struct *task;
+ struct svc_pool *chosen_pool;
int error = 0;
unsigned int state = serv->sv_nrthreads-1;
@@ -704,18 +656,32 @@ svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
/* create new threads */
while (nrservs > 0) {
nrservs--;
- __module_get(serv->sv_module);
- error = __svc_create_thread(serv->sv_function, serv,
- choose_pool(serv, pool, &state));
- if (error < 0) {
- module_put(serv->sv_module);
+ chosen_pool = choose_pool(serv, pool, &state);
+
+ rqstp = svc_prepare_thread(serv, chosen_pool);
+ if (IS_ERR(rqstp)) {
+ error = PTR_ERR(rqstp);
break;
}
+
+ task = kthread_create(serv->sv_function, rqstp, serv->sv_name);
+ if (IS_ERR(task)) {
+ error = PTR_ERR(task);
+ svc_exit_thread(rqstp);
+ break;
+ }
+
+ rqstp->rq_task = task;
+ if (serv->sv_nrpools > 1)
+ svc_pool_map_set_cpumask(task, chosen_pool->sp_id);
+
+ svc_sock_update_bufs(serv);
+ wake_up_process(task);
}
/* destroy old threads */
while (nrservs < 0 &&
- (victim = choose_victim(serv, pool, &state)) != NULL) {
- send_sig(serv->sv_kill_signal, victim, 1);
+ (task = choose_victim(serv, pool, &state)) != NULL) {
+ send_sig(serv->sv_kill_signal, task, 1);
nrservs++;
}
--
1.5.3.6
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