Nfsd (and lockd) run kernel threads that currently use
MOD_{INC,DEC}_USE_COUNT to manage references to the module on
behalf of those threads. This is deprecated and unsafe.
This patch introduces module_kernel_thread which ensures that
references counts are taken and dropped as appropriate for kernel
threads, and uses it for nfsd and lockd.
NeilBrown
### Comments for ChangeSet
If a kernel thread runs code that is in a module, it can be started
with module_kernel_thread, and this will safely managed the reference
counts on the module implied by the existance of the thread.
This is then used for nfsd and lockd.
----------- Diffstat output ------------
./fs/lockd/svc.c | 9 ++------
./fs/nfsd/nfssvc.c | 11 +++-------
./include/linux/module.h | 15 +++++++++++++
./include/linux/sunrpc/svc.h | 4 +--
./kernel/module.c | 47 +++++++++++++++++++++++++++++++++++++++++++
./net/sunrpc/svc.c | 7 ++++--
6 files changed, 76 insertions(+), 17 deletions(-)
diff ./fs/lockd/svc.c~current~ ./fs/lockd/svc.c
--- ./fs/lockd/svc.c~current~ 2003-06-05 12:04:57.000000000 +1000
+++ ./fs/lockd/svc.c 2003-06-05 12:04:51.000000000 +1000
@@ -80,7 +80,7 @@ static inline void clear_grace_period(vo
/*
* This is the lockd kernel thread
*/
-static void
+static int
lockd(struct svc_rqst *rqstp)
{
struct svc_serv *serv = rqstp->rq_server;
@@ -88,7 +88,6 @@ lockd(struct svc_rqst *rqstp)
unsigned long grace_period_expire;
/* Lock module and set up kernel thread */
- MOD_INC_USE_COUNT;
lock_kernel();
/*
@@ -181,9 +180,7 @@ lockd(struct svc_rqst *rqstp)
/* release rpciod */
rpciod_down();
- /* Release module */
- unlock_kernel();
- MOD_DEC_USE_COUNT;
+ return 0;
}
/*
@@ -238,7 +235,7 @@ lockd_up(void)
/*
* Create the kernel thread and wait for it to start.
*/
- error = svc_create_thread(lockd, serv);
+ error = svc_create_thread(lockd, serv, THIS_MODULE);
if (error) {
printk(KERN_WARNING
"lockd_up: create thread failed, error=%d\n", error);
diff ./fs/nfsd/nfssvc.c~current~ ./fs/nfsd/nfssvc.c
--- ./fs/nfsd/nfssvc.c~current~ 2003-06-05 12:04:57.000000000 +1000
+++ ./fs/nfsd/nfssvc.c 2003-06-05 12:04:51.000000000 +1000
@@ -48,7 +48,7 @@
#define SIG_NOCLEAN SIGHUP
extern struct svc_program nfsd_program;
-static void nfsd(struct svc_rqst *rqstp);
+static int nfsd(struct svc_rqst *rqstp);
struct timeval nfssvc_boot;
static struct svc_serv *nfsd_serv;
static atomic_t nfsd_busy;
@@ -114,7 +114,7 @@ nfsd_svc(unsigned short port, int nrserv
nrservs -= (nfsd_serv->sv_nrthreads-1);
while (nrservs > 0) {
nrservs--;
- error = svc_create_thread(nfsd, nfsd_serv);
+ error = svc_create_thread(nfsd, nfsd_serv, THIS_MODULE);
if (error < 0)
break;
}
@@ -163,7 +163,7 @@ update_thread_usage(int busy_threads)
/*
* This is the NFS server kernel thread
*/
-static void
+static int
nfsd(struct svc_rqst *rqstp)
{
struct svc_serv *serv = rqstp->rq_server;
@@ -172,7 +172,6 @@ nfsd(struct svc_rqst *rqstp)
sigset_t shutdown_mask, allowed_mask;
/* Lock module and set up kernel thread */
- MOD_INC_USE_COUNT;
lock_kernel();
daemonize("nfsd");
current->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
@@ -255,9 +254,7 @@ nfsd(struct svc_rqst *rqstp)
/* Release the thread */
svc_exit_thread(rqstp);
-
- /* Release module */
- MOD_DEC_USE_COUNT;
+ return 0;
}
int
diff ./include/linux/module.h~current~ ./include/linux/module.h
--- ./include/linux/module.h~current~ 2003-06-05 12:04:57.000000000 +1000
+++ ./include/linux/module.h 2003-06-05 11:34:24.000000000 +1000
@@ -314,6 +314,9 @@ static inline void module_put(struct mod
}
}
+extern int module_kernel_thread(int (*fn)(void*), void *arg,
+ unsigned long flags, struct module *owner);
+
#else /*!CONFIG_MODULE_UNLOAD*/
static inline int try_module_get(struct module *module)
{
@@ -328,6 +331,12 @@ static inline void __module_get(struct m
#define symbol_put(x) do { } while(0)
#define symbol_put_addr(p) do { } while(0)
+static inline int module_kernel_thread(int (*fn)(void*), void *arg,
+ unsigned long flags, struct module *owner)
+{
+ return kernel_thread(fn, arg, flags);
+}
+
#endif /* CONFIG_MODULE_UNLOAD */
/* This is a #define so the string doesn't get put in every .o file */
@@ -419,6 +428,12 @@ static inline int unregister_module_noti
return 0;
}
+static inline int module_kernel_thread(int (*fn)(void*), void *arg,
+ unsigned long flags, struct module *owner)
+{
+ return kernel_thread(fn, arg, flags);
+}
+
#endif /* CONFIG_MODULES */
#ifdef MODULE
diff ./include/linux/sunrpc/svc.h~current~ ./include/linux/sunrpc/svc.h
--- ./include/linux/sunrpc/svc.h~current~ 2003-06-05 12:04:57.000000000 +1000
+++ ./include/linux/sunrpc/svc.h 2003-06-05 12:04:51.000000000 +1000
@@ -276,13 +276,13 @@ struct svc_procedure {
/*
* This is the RPC server thread function prototype
*/
-typedef void (*svc_thread_fn)(struct svc_rqst *);
+typedef int (*svc_thread_fn)(struct svc_rqst *);
/*
* Function prototypes.
*/
struct svc_serv * svc_create(struct svc_program *, unsigned int);
-int svc_create_thread(svc_thread_fn, struct svc_serv *);
+int svc_create_thread(svc_thread_fn, struct svc_serv *, struct module *);
void svc_exit_thread(struct svc_rqst *);
void svc_destroy(struct svc_serv *);
int svc_process(struct svc_serv *, struct svc_rqst *);
diff ./kernel/module.c~current~ ./kernel/module.c
--- ./kernel/module.c~current~ 2003-06-05 12:04:57.000000000 +1000
+++ ./kernel/module.c 2003-06-05 11:34:24.000000000 +1000
@@ -616,6 +616,53 @@ void symbol_put_addr(void *addr)
}
EXPORT_SYMBOL_GPL(symbol_put_addr);
+
+/*
+ * If a kernel_thread runs in a module, we might want to
+ * module to be refcounted by the threads. This code
+ * allows that to happen.
+ * When module_kernel_thread completes, the module will
+ * have been ref-counted iif the thread started.
+ */
+struct kern_thread_info {
+ int (*fn)(void*);
+ void *arg;
+ struct module *owner;
+};
+static int module_kernel_thread_helper(void *arg)
+{
+ struct kern_thread_info *kti = arg;
+ int rv;
+
+ rv = kti->fn(kti->arg);
+ module_put(kti->owner);
+ kfree(kti);
+ return rv;
+}
+int module_kernel_thread(int (*fn)(void*), void *arg,
+ unsigned long flags, struct module *owner)
+{
+ struct kern_thread_info *kti;
+ int err;
+
+ if (!owner)
+ return kernel_thread(fn, arg, flags);
+ kti = kmalloc(sizeof(*kti), GFP_KERNEL);
+ if (!kti)
+ return -ENOMEM;
+ kti->fn = fn;
+ kti->arg = arg;
+ kti->owner = owner;
+ __module_get(owner);
+ err = kernel_thread(module_kernel_thread_helper, kti, flags);
+ if (err < 0) {
+ module_put(owner);
+ kfree(kti);
+ }
+ return err;
+}
+EXPORT_SYMBOL(module_kernel_thread);
+
#else /* !CONFIG_MODULE_UNLOAD */
static void print_unload_info(struct seq_file *m, struct module *mod)
{
diff ./net/sunrpc/svc.c~current~ ./net/sunrpc/svc.c
--- ./net/sunrpc/svc.c~current~ 2003-06-05 12:04:57.000000000 +1000
+++ ./net/sunrpc/svc.c 2003-06-05 12:06:13.000000000 +1000
@@ -14,6 +14,7 @@
#include <linux/in.h>
#include <linux/unistd.h>
#include <linux/mm.h>
+#include <linux/module.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/xdr.h>
@@ -150,7 +151,8 @@ svc_release_buffer(struct svc_rqst *rqst
* Create a server thread
*/
int
-svc_create_thread(svc_thread_fn func, struct svc_serv *serv)
+svc_create_thread(svc_thread_fn func, struct svc_serv *serv,
+ struct module *owner)
{
struct svc_rqst *rqstp;
int error = -ENOMEM;
@@ -169,7 +171,8 @@ svc_create_thread(svc_thread_fn func, st
serv->sv_nrthreads++;
rqstp->rq_server = serv;
- error = kernel_thread((int (*)(void *)) func, rqstp, 0);
+ error = module_kernel_thread((int(*)(void*))func, rqstp,
+ 0, owner);
if (error < 0)
goto out_thread;
svc_sock_update_bufs(serv);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Sat Jun 07 2003 - 22:00:26 EST