From 1a2142afa5646ad5af44bbe1febaa5e0b7e71156 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon, 30 Mar 2009 22:05:10 -0600
Subject: cpumask: remove dangerous CPU_MASK_ALL_PTR, &CPU_MASK_ALL
Impact: cleanup
(Thanks to Al Viro for reminding me of this, via Ingo)
CPU_MASK_ALL is the (deprecated) "all bits set" cpumask, defined as so:
#define CPU_MASK_ALL (cpumask_t) { { ... } }
Taking the address of such a temporary is questionable at best,
unfortunately 321a8e9d (cpumask: add CPU_MASK_ALL_PTR macro) added
CPU_MASK_ALL_PTR:
#define CPU_MASK_ALL_PTR (&CPU_MASK_ALL)
Which formalizes this practice. One day gcc could bite us over this
usage (though we seem to have gotten away with it so far).
So replace everywhere which used &CPU_MASK_ALL or CPU_MASK_ALL_PTR
with the modern "cpu_all_mask" (a real const struct cpumask *).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Ingo Molnar <mingo@elte.hu>
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Mike Travis <travis@sgi.com>
---
kernel/kmod.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
(limited to 'kernel/kmod.c')
diff --git a/kernel/kmod.c b/kernel/kmod.c
index a27a5f64443d..f0c8f545180d 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -167,7 +167,7 @@ static int ____call_usermodehelper(void *data)
}
/* We can run anywhere, unlike our parent keventd(). */
- set_cpus_allowed_ptr(current, CPU_MASK_ALL_PTR);
+ set_cpus_allowed_ptr(current, cpu_all_mask);
/*
* Our parent is keventd, which runs with elevated scheduling priority.
--
cgit v1.2.3
From acae05156551fd7528fbb616271e672789388e3c Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <arjan@linux.intel.com>
Date: Sun, 8 Feb 2009 10:42:01 -0800
Subject: module: create a request_module_nowait()
There seems to be a common pattern in the kernel where drivers want to
call request_module() from inside a module_init() function. Currently
this would deadlock.
As a result, several drivers go through hoops like scheduling things via
kevent, or creating custom work queues (because kevent can deadlock on them).
This patch changes this to use a request_module_nowait() function macro instead,
which just fires the modprobe off but doesn't wait for it, and thus avoids the
original deadlock entirely.
On my laptop this already results in one less kernel thread running..
(Includes Jiri's patch to use enum umh_wait)
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (bool-ified)
Cc: Jiri Slaby <jirislaby@gmail.com>
---
include/linux/kmod.h | 11 ++++++++---
kernel/kmod.c | 10 ++++++----
2 files changed, 14 insertions(+), 7 deletions(-)
(limited to 'kernel/kmod.c')
diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index 92213a9194e1..d5fa565086d1 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -29,10 +29,15 @@
#ifdef CONFIG_MODULES
/* modprobe exit status on success, -ve on error. Return value
* usually useless though. */
-extern int request_module(const char * name, ...) __attribute__ ((format (printf, 1, 2)));
-#define try_then_request_module(x, mod...) ((x) ?: (request_module(mod), (x)))
+extern int __request_module(bool wait, const char *name, ...) \
+ __attribute__((format(printf, 2, 3)));
+#define request_module(mod...) __request_module(true, mod)
+#define request_module_nowait(mod...) __request_module(false, mod)
+#define try_then_request_module(x, mod...) \
+ ((x) ?: (__request_module(false, mod), (x)))
#else
-static inline int request_module(const char * name, ...) { return -ENOSYS; }
+static inline int request_module(const char *name, ...) { return -ENOSYS; }
+static inline int request_module_nowait(const char *name, ...) { return -ENOSYS; }
#define try_then_request_module(x, mod...) (x)
#endif
diff --git a/kernel/kmod.c b/kernel/kmod.c
index f0c8f545180d..b750675251e5 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -50,7 +50,8 @@ static struct workqueue_struct *khelper_wq;
char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
/**
- * request_module - try to load a kernel module
+ * __request_module - try to load a kernel module
+ * @wait: wait (or not) for the operation to complete
* @fmt: printf style format string for the name of the module
* @...: arguments as specified in the format string
*
@@ -63,7 +64,7 @@ char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
* If module auto-loading support is disabled then this function
* becomes a no-operation.
*/
-int request_module(const char *fmt, ...)
+int __request_module(bool wait, const char *fmt, ...)
{
va_list args;
char module_name[MODULE_NAME_LEN];
@@ -108,11 +109,12 @@ int request_module(const char *fmt, ...)
return -ENOMEM;
}
- ret = call_usermodehelper(modprobe_path, argv, envp, 1);
+ ret = call_usermodehelper(modprobe_path, argv, envp,
+ wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
atomic_dec(&kmod_concurrent);
return ret;
}
-EXPORT_SYMBOL(request_module);
+EXPORT_SYMBOL(__request_module);
#endif /* CONFIG_MODULES */
struct subprocess_info {
--
cgit v1.2.3