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Message-ID: <25668.1259675528@redhat.com>
Date: Tue, 01 Dec 2009 13:52:08 +0000
From: David Howells <dhowells@...hat.com>
To: torvalds@...l.org, akpm@...ux-foundation.org, mingo@...e.hu
cc: dhowells@...hat.com, steved@...hat.com, jens.axboe@...cle.com,
linux-cachefs@...hat.com, nfsv4@...ux-nfs.org,
linux-fsdevel@...r.kernel.org, cluster-devel@...hat.com,
linux-kernel@...r.kernel.org, linux-cifs-client@...ts.samba.org
Subject: [PATCH] SLOW_WORK: Fix the CONFIG_MODULES=n case
From: David Howells <dhowells@...hat.com>
Commits 3d7a641 ("SLOW_WORK: Wait for outstanding work items belonging to a
module to clear") introduced some code to make sure that all of a module's
slow-work items were complete before that module was removed, and commit
3bde31a ("SLOW_WORK: Allow a requeueable work item to sleep till the thread is
needed") further extended that, breaking it in the process if CONFIG_MODULES=n:
CC kernel/slow-work.o
kernel/slow-work.c: In function 'slow_work_execute':
kernel/slow-work.c:313: error: 'slow_work_thread_processing' undeclared (first use in this function)
kernel/slow-work.c:313: error: (Each undeclared identifier is reported only once
kernel/slow-work.c:313: error: for each function it appears in.)
kernel/slow-work.c: In function 'slow_work_wait_for_items':
kernel/slow-work.c:950: error: 'slow_work_unreg_sync_lock' undeclared (first use in this function)
kernel/slow-work.c:951: error: 'slow_work_unreg_wq' undeclared (first use in this function)
kernel/slow-work.c:961: error: 'slow_work_unreg_work_item' undeclared (first use in this function)
kernel/slow-work.c:974: error: 'slow_work_unreg_module' undeclared (first use in this function)
kernel/slow-work.c:977: error: 'slow_work_thread_processing' undeclared (first use in this function)
make[1]: *** [kernel/slow-work.o] Error 1
Fix this by:
(1) Extracting the bits of slow_work_execute() that are contingent on
CONFIG_MODULES, and the bits that should be, into inline functions and
placing them into the #ifdef'd section that defines the relevant variables
and adding stubs for moduleless kernels. This allows the removal of some
#ifdefs.
(2) #ifdef'ing out the contents of slow_work_wait_for_items() in moduleless
kernels.
The four functions related to handling module unloading synchronisation (and
their associated variables) could be offloaded into a separate .c file, but
each function is only used once and three of them are tiny, so doing so would
prevent them from being inlined.
Reported-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: David Howells <dhowells@...hat.com>
---
kernel/slow-work.c | 46 +++++++++++++++++++++++++++++-----------------
1 files changed, 29 insertions(+), 17 deletions(-)
diff --git a/kernel/slow-work.c b/kernel/slow-work.c
index da94f3c..b5c17f1 100644
--- a/kernel/slow-work.c
+++ b/kernel/slow-work.c
@@ -109,6 +109,30 @@ static struct module *slow_work_unreg_module;
static struct slow_work *slow_work_unreg_work_item;
static DECLARE_WAIT_QUEUE_HEAD(slow_work_unreg_wq);
static DEFINE_MUTEX(slow_work_unreg_sync_lock);
+
+static void slow_work_set_thread_processing(int id, struct slow_work *work)
+{
+ if (work)
+ slow_work_thread_processing[id] = work->owner;
+}
+static void slow_work_done_thread_processing(int id, struct slow_work *work)
+{
+ struct module *module = slow_work_thread_processing[id];
+
+ slow_work_thread_processing[id] = NULL;
+ smp_mb();
+ if (slow_work_unreg_work_item == work ||
+ slow_work_unreg_module == module)
+ wake_up_all(&slow_work_unreg_wq);
+}
+static void slow_work_clear_thread_processing(int id)
+{
+ slow_work_thread_processing[id] = NULL;
+}
+#else
+static void slow_work_set_thread_processing(int id, struct slow_work *work) {}
+static void slow_work_done_thread_processing(int id, struct slow_work *work) {}
+static void slow_work_clear_thread_processing(int id) {}
#endif
/*
@@ -197,9 +221,6 @@ static unsigned slow_work_calc_vsmax(void)
*/
static noinline bool slow_work_execute(int id)
{
-#ifdef CONFIG_MODULES
- struct module *module;
-#endif
struct slow_work *work = NULL;
unsigned vsmax;
bool very_slow;
@@ -236,10 +257,7 @@ static noinline bool slow_work_execute(int id)
very_slow = false; /* avoid the compiler warning */
}
-#ifdef CONFIG_MODULES
- if (work)
- slow_work_thread_processing[id] = work->owner;
-#endif
+ slow_work_set_thread_processing(id, work);
if (work) {
slow_work_mark_time(work);
slow_work_begin_exec(id, work);
@@ -287,15 +305,7 @@ static noinline bool slow_work_execute(int id)
/* sort out the race between module unloading and put_ref() */
slow_work_put_ref(work);
-
-#ifdef CONFIG_MODULES
- module = slow_work_thread_processing[id];
- slow_work_thread_processing[id] = NULL;
- smp_mb();
- if (slow_work_unreg_work_item == work ||
- slow_work_unreg_module == module)
- wake_up_all(&slow_work_unreg_wq);
-#endif
+ slow_work_done_thread_processing(id, work);
return true;
@@ -310,7 +320,7 @@ auto_requeue:
else
list_add_tail(&work->link, &slow_work_queue);
spin_unlock_irq(&slow_work_queue_lock);
- slow_work_thread_processing[id] = NULL;
+ slow_work_clear_thread_processing(id);
return true;
}
@@ -943,6 +953,7 @@ EXPORT_SYMBOL(slow_work_register_user);
*/
static void slow_work_wait_for_items(struct module *module)
{
+#ifdef CONFIG_MODULES
DECLARE_WAITQUEUE(myself, current);
struct slow_work *work;
int loop;
@@ -989,6 +1000,7 @@ static void slow_work_wait_for_items(struct module *module)
remove_wait_queue(&slow_work_unreg_wq, &myself);
mutex_unlock(&slow_work_unreg_sync_lock);
+#endif /* CONFIG_MODULES */
}
/**
--
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