Please apply. Neil wants this for safety of his kernel threads in
modules (which hold a reference count).
Name: module_put_and_exit
Author: Neil Brown
Status: Booted on 2.5.74-bk1
D: Define module_put_and_exit() and use it for nfsd/lockd
D:
D: Both nfsd and lockd have threads which expect to hold a reference
D: to the module while the thread is running. In order for the thread
D: to be able to put_module() the module before exiting, the
D: put_module code must be call from outside the module.
D:
D: This patch provides module_put_and_exit in non-modular code which a
D: thread-in-a-module can call. It also gets nfsd and lockd to use it
D: as appropriate.
D:
D: Note that in lockd, we can __get_module in the thread itself as the
D: creator of the thread is waiting for the thread to startup.
D:
D: In nfsd and for the 'reclaimer' threaded started by locked, we
D: __get_module first and put_module if the thread failed to start.
D:
D: ----------- Diffstat output ------------
D: ./fs/lockd/clntlock.c | 9 ++++-----
D: ./fs/lockd/svc.c | 8 ++++++--
D: ./fs/nfsd/nfssvc.c | 8 +++++---
D: ./include/linux/module.h | 8 ++++++++
D: ./kernel/exit.c | 1 +
D: ./kernel/module.c | 12 ++++++++++++
D: 6 files changed, 36 insertions(+), 10 deletions(-)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .25804-linux-2.5.74-bk1/fs/lockd/clntlock.c .25804-linux-2.5.74-bk1.updated/fs/lockd/clntlock.c
--- .25804-linux-2.5.74-bk1/fs/lockd/clntlock.c 2003-02-17 11:37:52.000000000 +1100
+++ .25804-linux-2.5.74-bk1.updated/fs/lockd/clntlock.c 2003-07-04 07:58:04.000000000 +1000
@@ -187,8 +187,9 @@ nlmclnt_recovery(struct nlm_host *host,
} else {
nlmclnt_prepare_reclaim(host, newstate);
nlm_get_host(host);
- MOD_INC_USE_COUNT;
- kernel_thread(reclaimer, host, CLONE_KERNEL);
+ __module_get(THIS_MODULE);
+ if (kernel_thread(reclaimer, host, CLONE_KERNEL))
+ module_put(THIS_MODULE);
}
}
@@ -244,7 +245,5 @@ restart:
nlm_release_host(host);
lockd_down();
unlock_kernel();
- MOD_DEC_USE_COUNT;
-
- return 0;
+ module_put_and_exit(0);
}
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .25804-linux-2.5.74-bk1/fs/lockd/svc.c .25804-linux-2.5.74-bk1.updated/fs/lockd/svc.c
--- .25804-linux-2.5.74-bk1/fs/lockd/svc.c 2003-07-03 09:43:54.000000000 +1000
+++ .25804-linux-2.5.74-bk1.updated/fs/lockd/svc.c 2003-07-04 07:58:04.000000000 +1000
@@ -88,7 +88,11 @@ lockd(struct svc_rqst *rqstp)
unsigned long grace_period_expire;
/* Lock module and set up kernel thread */
- MOD_INC_USE_COUNT;
+ /* lockd_up is waiting for us to startup, so will
+ * be holding a reference to this module, so it
+ * is safe to just claim another reference
+ */
+ __module_get(THIS_MODULE);
lock_kernel();
/*
@@ -183,7 +187,7 @@ lockd(struct svc_rqst *rqstp)
/* Release module */
unlock_kernel();
- MOD_DEC_USE_COUNT;
+ module_put_and_exit(0);
}
/*
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .25804-linux-2.5.74-bk1/fs/nfsd/nfssvc.c .25804-linux-2.5.74-bk1.updated/fs/nfsd/nfssvc.c
--- .25804-linux-2.5.74-bk1/fs/nfsd/nfssvc.c 2003-07-03 09:43:54.000000000 +1000
+++ .25804-linux-2.5.74-bk1.updated/fs/nfsd/nfssvc.c 2003-07-04 07:58:04.000000000 +1000
@@ -115,9 +115,12 @@ nfsd_svc(unsigned short port, int nrserv
nrservs -= (nfsd_serv->sv_nrthreads-1);
while (nrservs > 0) {
nrservs--;
+ __module_get(THIS_MODULE);
error = svc_create_thread(nfsd, nfsd_serv);
- if (error < 0)
+ if (error < 0) {
+ module_put(THIS_MODULE);
break;
+ }
}
victim = nfsd_list.next;
while (nrservs < 0 && victim != &nfsd_list) {
@@ -173,7 +176,6 @@ 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;
@@ -266,7 +268,7 @@ nfsd(struct svc_rqst *rqstp)
svc_exit_thread(rqstp);
/* Release module */
- MOD_DEC_USE_COUNT;
+ module_put_and_exit(0);
}
int
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .25804-linux-2.5.74-bk1/include/linux/module.h .25804-linux-2.5.74-bk1.updated/include/linux/module.h
--- .25804-linux-2.5.74-bk1/include/linux/module.h 2003-07-03 09:44:00.000000000 +1000
+++ .25804-linux-2.5.74-bk1.updated/include/linux/module.h 2003-07-04 08:00:09.000000000 +1000
@@ -276,8 +276,12 @@ struct module *module_get_kallsym(unsign
char *type,
char namebuf[128]);
int is_exported(const char *name, const struct module *mod);
-#ifdef CONFIG_MODULE_UNLOAD
+extern void __module_put_and_exit(struct module *mod, long code)
+ __attribute__((noreturn));
+#define module_put_and_exit(code) __module_put_and_exit(THIS_MODULE, code);
+
+#ifdef CONFIG_MODULE_UNLOAD
unsigned int module_refcount(struct module *mod);
void __symbol_put(const char *symbol);
#define symbol_put(x) __symbol_put(MODULE_SYMBOL_PREFIX #x)
@@ -445,6 +449,8 @@ static inline int unregister_module_noti
return 0;
}
+#define module_put_and_exit(code) do_exit(code)
+
#endif /* CONFIG_MODULES */
#ifdef MODULE
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .25804-linux-2.5.74-bk1/kernel/module.c .25804-linux-2.5.74-bk1.updated/kernel/module.c
--- .25804-linux-2.5.74-bk1/kernel/module.c 2003-07-03 09:44:01.000000000 +1000
+++ .25804-linux-2.5.74-bk1.updated/kernel/module.c 2003-07-04 07:59:20.000000000 +1000
@@ -98,6 +98,17 @@ int init_module(void)
}
EXPORT_SYMBOL(init_module);
+/* A thread that wants to hold a reference to a module only while it
+ * is running can call ths to safely exit.
+ * nfsd and lockd use this.
+ */
+void __module_put_and_exit(struct module *mod, long code)
+{
+ module_put(mod);
+ do_exit(code);
+}
+EXPORT_SYMBOL(__module_put_and_exit);
+
/* Find a module section: 0 means not found. */
static unsigned int find_sec(Elf_Ehdr *hdr,
Elf_Shdr *sechdrs,
-- Anyone who quotes me in their sig is an idiot. -- Rusty Russell. - 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 : Wed Jul 23 2003 - 22:00:31 EST