[PATCH] drivers: wait for threaded probes between initcall levels
The multithreaded-probing code has a problem: after one initcall level (eg,
core_initcall) has been processed, we will then start processing the next
level (postcore_initcall) while the kernel threads which are handling
core_initcall are still executing. This breaks the guarantees which the
layered initcalls previously gave us.
IOW, we want to be multithreaded _within_ an initcall level, but not between
different levels.
Fix that up by causing the probing code to wait for all outstanding probes at
one level to complete before we start processing the next level.
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index db01b95..c5d6bb4 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -18,6 +18,7 @@
#include <linux/device.h>
#include <linux/module.h>
#include <linux/kthread.h>
+#include <linux/wait.h>
#include "base.h"
#include "power/power.h"
@@ -70,6 +71,8 @@
};
static atomic_t probe_count = ATOMIC_INIT(0);
+static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
+
static int really_probe(void *void_data)
{
struct stupid_thread_structure *data = void_data;
@@ -121,6 +124,7 @@
done:
kfree(data);
atomic_dec(&probe_count);
+ wake_up(&probe_waitqueue);
return ret;
}
@@ -337,6 +341,32 @@
}
}
+#ifdef CONFIG_PCI_MULTITHREAD_PROBE
+static int __init wait_for_probes(void)
+{
+ DEFINE_WAIT(wait);
+
+ printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__,
+ atomic_read(&probe_count));
+ if (!atomic_read(&probe_count))
+ return 0;
+ while (atomic_read(&probe_count)) {
+ prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE);
+ if (atomic_read(&probe_count))
+ schedule();
+ }
+ finish_wait(&probe_waitqueue, &wait);
+ return 0;
+}
+
+core_initcall_sync(wait_for_probes);
+postcore_initcall_sync(wait_for_probes);
+arch_initcall_sync(wait_for_probes);
+subsys_initcall_sync(wait_for_probes);
+fs_initcall_sync(wait_for_probes);
+device_initcall_sync(wait_for_probes);
+late_initcall_sync(wait_for_probes);
+#endif
EXPORT_SYMBOL_GPL(device_bind_driver);
EXPORT_SYMBOL_GPL(device_release_driver);