Message-ID: <5838.1509550663@warthog.procyon.org.uk>
Date:   Wed, 01 Nov 2017 15:37:43 +0000
From:   David Howells <dhowells@...hat.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
cc:     dhowells@...hat.com, linux-kernel@...r.kernel.org
Subject: [PATCH] Pass mode to wait_on_atomic_t() action funcs and provide default actions

Hi Ingo, Peter,

I'd like to propose this change for the next merge window.  One question,
though: rather than providing an exported default function, should the default
be used automatically if a NULL function pointer is passed?

Thanks,
David
---

Pass mode to wait_on_atomic_t() action funcs and provide default actions

Make wait_on_atomic_t() pass the TASK_* mode onto its action function as an
extra argument and make it 'unsigned int throughout.

Also, consolidate a bunch of identical action functions into a default
function that can do the appropriate thing for the mode.

Also, change the argument name in the bit_wait*() function declarations to
reflect the fact that it's the mode and not the bit number.

Signed-off-by: David Howells <dhowells@...hat.com>
cc: Ingo Molnar <mingo@...nel.org>

---
 arch/mips/kernel/traps.c                           |   14 ----------
 drivers/gpu/drm/drm_dp_aux_dev.c                   |    8 ------
 drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c |   10 +------
 drivers/media/platform/qcom/venus/hfi.c            |    8 ------
 fs/afs/rxrpc.c                                     |    8 ------
 fs/btrfs/extent-tree.c                             |   27 ++-------------------
 fs/fscache/cookie.c                                |    2 -
 fs/fscache/internal.h                              |    2 -
 fs/fscache/main.c                                  |    9 -------
 fs/nfs/inode.c                                     |    4 +--
 fs/nfs/internal.h                                  |    2 -
 fs/ocfs2/filecheck.c                               |    8 ------
 include/linux/wait_bit.h                           |   15 +++++++----
 kernel/sched/wait_bit.c                            |   18 ++++++++++----
 14 files changed, 37 insertions(+), 98 deletions(-)

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 5669d3b8bd38..5d19ed07e99d 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -1233,18 +1233,6 @@ static int default_cu2_call(struct notifier_block *nfb, unsigned long action,
 	return NOTIFY_OK;
 }
 
-static int wait_on_fp_mode_switch(atomic_t *p)
-{
-	/*
-	 * The FP mode for this task is currently being switched. That may
-	 * involve modifications to the format of this tasks FP context which
-	 * make it unsafe to proceed with execution for the moment. Instead,
-	 * schedule some other task.
-	 */
-	schedule();
-	return 0;
-}
-
 static int enable_restore_fp_context(int msa)
 {
 	int err, was_fpu_owner, prior_msa;
@@ -1254,7 +1242,7 @@ static int enable_restore_fp_context(int msa)
 	 * complete before proceeding.
 	 */
 	wait_on_atomic_t(&current->mm->context.fp_mode_switching,
-			 wait_on_fp_mode_switch, TASK_KILLABLE);
+			 atomic_t_wait, TASK_KILLABLE);
 
 	if (!used_math()) {
 		/* First time FP context user. */
diff --git a/drivers/gpu/drm/drm_dp_aux_dev.c b/drivers/gpu/drm/drm_dp_aux_dev.c
index d34e5096887a..053044201e31 100644
--- a/drivers/gpu/drm/drm_dp_aux_dev.c
+++ b/drivers/gpu/drm/drm_dp_aux_dev.c
@@ -263,12 +263,6 @@ static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_aux(struct drm_dp_aux *aux)
 	return aux_dev;
 }
 
-static int auxdev_wait_atomic_t(atomic_t *p)
-{
-	schedule();
-	return 0;
-}
-
 void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
 {
 	struct drm_dp_aux_dev *aux_dev;
@@ -283,7 +277,7 @@ void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
 	mutex_unlock(&aux_idr_mutex);
 
 	atomic_dec(&aux_dev->usecount);
-	wait_on_atomic_t(&aux_dev->usecount, auxdev_wait_atomic_t,
+	wait_on_atomic_t(&aux_dev->usecount, atomic_t_wait,
 			 TASK_UNINTERRUPTIBLE);
 
 	minor = aux_dev->index;
diff --git a/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c b/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c
index 828904b7d468..54fc571b1102 100644
--- a/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c
@@ -271,13 +271,7 @@ struct igt_wakeup {
 	u32 seqno;
 };
 
-static int wait_atomic(atomic_t *p)
-{
-	schedule();
-	return 0;
-}
-
-static int wait_atomic_timeout(atomic_t *p)
+static int wait_atomic_timeout(atomic_t *p, unsigned int mode)
 {
 	return schedule_timeout(10 * HZ) ? 0 : -ETIMEDOUT;
 }
@@ -348,7 +342,7 @@ static void igt_wake_all_sync(atomic_t *ready,
 	atomic_set(ready, 0);
 	wake_up_all(wq);
 
-	wait_on_atomic_t(set, wait_atomic, TASK_UNINTERRUPTIBLE);
+	wait_on_atomic_t(set, atomic_t_wait, TASK_UNINTERRUPTIBLE);
 	atomic_set(ready, count);
 	atomic_set(done, count);
 }
diff --git a/drivers/media/platform/qcom/venus/hfi.c b/drivers/media/platform/qcom/venus/hfi.c
index c09490876516..e374c7d1a618 100644
--- a/drivers/media/platform/qcom/venus/hfi.c
+++ b/drivers/media/platform/qcom/venus/hfi.c
@@ -88,12 +88,6 @@ int hfi_core_init(struct venus_core *core)
 	return ret;
 }
 
-static int core_deinit_wait_atomic_t(atomic_t *p)
-{
-	schedule();
-	return 0;
-}
-
 int hfi_core_deinit(struct venus_core *core, bool blocking)
 {
 	int ret = 0, empty;
@@ -112,7 +106,7 @@ int hfi_core_deinit(struct venus_core *core, bool blocking)
 
 	if (!empty) {
 		mutex_unlock(&core->lock);
-		wait_on_atomic_t(&core->insts_count, core_deinit_wait_atomic_t,
+		wait_on_atomic_t(&core->insts_count, atomic_t_wait,
 				 TASK_UNINTERRUPTIBLE);
 		mutex_lock(&core->lock);
 	}
diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index bb1e2caa1720..77f5420a1a24 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -41,12 +41,6 @@ static void afs_charge_preallocation(struct work_struct *);
 
 static DECLARE_WORK(afs_charge_preallocation_work, afs_charge_preallocation);
 
-static int afs_wait_atomic_t(atomic_t *p)
-{
-	schedule();
-	return 0;
-}
-
 /*
  * open an RxRPC socket and bind it to be a server for callback notifications
  * - the socket is left in blocking mode and non-blocking ops use MSG_DONTWAIT
@@ -121,7 +115,7 @@ void afs_close_socket(void)
 	}
 
 	_debug("outstanding %u", atomic_read(&afs_outstanding_calls));
-	wait_on_atomic_t(&afs_outstanding_calls, afs_wait_atomic_t,
+	wait_on_atomic_t(&afs_outstanding_calls, atomic_t_wait,
 			 TASK_UNINTERRUPTIBLE);
 	_debug("no outstanding calls");
 
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index e2d7e86b51d1..24cefde30e30 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4016,16 +4016,9 @@ void btrfs_dec_nocow_writers(struct btrfs_fs_info *fs_info, u64 bytenr)
 	btrfs_put_block_group(bg);
 }
 
-static int btrfs_wait_nocow_writers_atomic_t(atomic_t *a)
-{
-	schedule();
-	return 0;
-}
-
 void btrfs_wait_nocow_writers(struct btrfs_block_group_cache *bg)
 {
-	wait_on_atomic_t(&bg->nocow_writers,
-			 btrfs_wait_nocow_writers_atomic_t,
+	wait_on_atomic_t(&bg->nocow_writers, atomic_t_wait,
 			 TASK_UNINTERRUPTIBLE);
 }
 
@@ -6595,12 +6588,6 @@ void btrfs_dec_block_group_reservations(struct btrfs_fs_info *fs_info,
 	btrfs_put_block_group(bg);
 }
 
-static int btrfs_wait_bg_reservations_atomic_t(atomic_t *a)
-{
-	schedule();
-	return 0;
-}
-
 void btrfs_wait_block_group_reservations(struct btrfs_block_group_cache *bg)
 {
 	struct btrfs_space_info *space_info = bg->space_info;
@@ -6623,8 +6610,7 @@ void btrfs_wait_block_group_reservations(struct btrfs_block_group_cache *bg)
 	down_write(&space_info->groups_sem);
 	up_write(&space_info->groups_sem);
 
-	wait_on_atomic_t(&bg->reservations,
-			 btrfs_wait_bg_reservations_atomic_t,
+	wait_on_atomic_t(&bg->reservations, atomic_t_wait,
 			 TASK_UNINTERRUPTIBLE);
 }
 
@@ -11106,12 +11092,6 @@ int btrfs_start_write_no_snapshotting(struct btrfs_root *root)
 	return 1;
 }
 
-static int wait_snapshotting_atomic_t(atomic_t *a)
-{
-	schedule();
-	return 0;
-}
-
 void btrfs_wait_for_snapshot_creation(struct btrfs_root *root)
 {
 	while (true) {
@@ -11120,8 +11100,7 @@ void btrfs_wait_for_snapshot_creation(struct btrfs_root *root)
 		ret = btrfs_start_write_no_snapshotting(root);
 		if (ret)
 			break;
-		wait_on_atomic_t(&root->will_be_snapshotted,
-				 wait_snapshotting_atomic_t,
+		wait_on_atomic_t(&root->will_be_snapshotted, atomic_t_wait,
 				 TASK_UNINTERRUPTIBLE);
 	}
 }
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index 40d61077bead..ff84258132bb 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -558,7 +558,7 @@ void __fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate)
 	 * have completed.
 	 */
 	if (!atomic_dec_and_test(&cookie->n_active))
-		wait_on_atomic_t(&cookie->n_active, fscache_wait_atomic_t,
+		wait_on_atomic_t(&cookie->n_active, atomic_t_wait,
 				 TASK_UNINTERRUPTIBLE);
 
 	/* Make sure any pending writes are cancelled. */
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index 97ec45110957..0ff4b49a0037 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -97,8 +97,6 @@ static inline bool fscache_object_congested(void)
 	return workqueue_congested(WORK_CPU_UNBOUND, fscache_object_wq);
 }
 
-extern int fscache_wait_atomic_t(atomic_t *);
-
 /*
  * object.c
  */
diff --git a/fs/fscache/main.c b/fs/fscache/main.c
index b39d487ccfb0..249968dcbf5c 100644
--- a/fs/fscache/main.c
+++ b/fs/fscache/main.c
@@ -195,12 +195,3 @@ static void __exit fscache_exit(void)
 }
 
 module_exit(fscache_exit);
-
-/*
- * wait_on_atomic_t() sleep function for uninterruptible waiting
- */
-int fscache_wait_atomic_t(atomic_t *p)
-{
-	schedule();
-	return 0;
-}
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 134d9f560240..1629056aa2c9 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -85,9 +85,9 @@ int nfs_wait_bit_killable(struct wait_bit_key *key, int mode)
 }
 EXPORT_SYMBOL_GPL(nfs_wait_bit_killable);
 
-int nfs_wait_atomic_killable(atomic_t *p)
+int nfs_wait_atomic_killable(atomic_t *p, unsigned int mode)
 {
-	return nfs_wait_killable(TASK_KILLABLE);
+	return nfs_wait_killable(mode);
 }
 
 /**
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 5bdf952f414b..22eeb895da5a 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -387,7 +387,7 @@ extern void nfs_evict_inode(struct inode *);
 void nfs_zap_acl_cache(struct inode *inode);
 extern bool nfs_check_cache_invalid(struct inode *, unsigned long);
 extern int nfs_wait_bit_killable(struct wait_bit_key *key, int mode);
-extern int nfs_wait_atomic_killable(atomic_t *p);
+extern int nfs_wait_atomic_killable(atomic_t *p, unsigned int mode);
 
 /* super.c */
 extern const struct super_operations nfs_sops;
diff --git a/fs/ocfs2/filecheck.c b/fs/ocfs2/filecheck.c
index 2cabbcf2f28e..e87279e49ba3 100644
--- a/fs/ocfs2/filecheck.c
+++ b/fs/ocfs2/filecheck.c
@@ -129,19 +129,13 @@ static struct kobj_attribute ocfs2_attr_filecheck_set =
 					ocfs2_filecheck_show,
 					ocfs2_filecheck_store);
 
-static int ocfs2_filecheck_sysfs_wait(atomic_t *p)
-{
-	schedule();
-	return 0;
-}
-
 static void
 ocfs2_filecheck_sysfs_free(struct ocfs2_filecheck_sysfs_entry *entry)
 {
 	struct ocfs2_filecheck_entry *p;
 
 	if (!atomic_dec_and_test(&entry->fs_count))
-		wait_on_atomic_t(&entry->fs_count, ocfs2_filecheck_sysfs_wait,
+		wait_on_atomic_t(&entry->fs_count, atomic_t_wait,
 				 TASK_UNINTERRUPTIBLE);
 
 	spin_lock(&entry->fs_fcheck->fc_lock);
diff --git a/include/linux/wait_bit.h b/include/linux/wait_bit.h
index 12b26660d7e9..40b9dd5b5ba1 100644
--- a/include/linux/wait_bit.h
+++ b/include/linux/wait_bit.h
@@ -25,6 +25,8 @@ struct wait_bit_queue_entry {
 	{ .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, }
 
 typedef int wait_bit_action_f(struct wait_bit_key *key, int mode);
+typedef int wait_atomic_t_action_f(atomic_t *counter, unsigned int mode);
+
 void __wake_up_bit(struct wait_queue_head *wq_head, void *word, int bit);
 int __wait_on_bit(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry, wait_bit_action_f *action, unsigned int mode);
 int __wait_on_bit_lock(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry, wait_bit_action_f *action, unsigned int mode);
@@ -33,7 +35,7 @@ void wake_up_atomic_t(atomic_t *p);
 int out_of_line_wait_on_bit(void *word, int, wait_bit_action_f *action, unsigned int mode);
 int out_of_line_wait_on_bit_timeout(void *word, int, wait_bit_action_f *action, unsigned int mode, unsigned long timeout);
 int out_of_line_wait_on_bit_lock(void *word, int, wait_bit_action_f *action, unsigned int mode);
-int out_of_line_wait_on_atomic_t(atomic_t *p, int (*)(atomic_t *), unsigned int mode);
+int out_of_line_wait_on_atomic_t(atomic_t *p, wait_atomic_t_action_f action, unsigned int mode);
 struct wait_queue_head *bit_waitqueue(void *word, int bit);
 extern void __init wait_bit_init(void);
 
@@ -50,10 +52,11 @@ int wake_bit_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync
 		},								\
 	}
 
-extern int bit_wait(struct wait_bit_key *key, int bit);
-extern int bit_wait_io(struct wait_bit_key *key, int bit);
-extern int bit_wait_timeout(struct wait_bit_key *key, int bit);
-extern int bit_wait_io_timeout(struct wait_bit_key *key, int bit);
+extern int bit_wait(struct wait_bit_key *key, int mode);
+extern int bit_wait_io(struct wait_bit_key *key, int mode);
+extern int bit_wait_timeout(struct wait_bit_key *key, int mode);
+extern int bit_wait_io_timeout(struct wait_bit_key *key, int mode);
+extern int atomic_t_wait(atomic_t *counter, unsigned int mode);
 
 /**
  * wait_on_bit - wait for a bit to be cleared
@@ -250,7 +253,7 @@ wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action,
  * outside of the target 'word'.
  */
 static inline
-int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
+int wait_on_atomic_t(atomic_t *val, wait_atomic_t_action_f action, unsigned mode)
 {
 	might_sleep();
 	if (atomic_read(val) == 0)
diff --git a/kernel/sched/wait_bit.c b/kernel/sched/wait_bit.c
index f8159698aa4d..84cb3acd9260 100644
--- a/kernel/sched/wait_bit.c
+++ b/kernel/sched/wait_bit.c
@@ -183,7 +183,7 @@ static int wake_atomic_t_function(struct wait_queue_entry *wq_entry, unsigned mo
  */
 static __sched
 int __wait_on_atomic_t(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry,
-		       int (*action)(atomic_t *), unsigned mode)
+		       wait_atomic_t_action_f action, unsigned int mode)
 {
 	atomic_t *val;
 	int ret = 0;
@@ -193,7 +193,7 @@ int __wait_on_atomic_t(struct wait_queue_head *wq_head, struct wait_bit_queue_en
 		val = wbq_entry->key.flags;
 		if (atomic_read(val) == 0)
 			break;
-		ret = (*action)(val);
+		ret = (*action)(val, mode);
 	} while (!ret && atomic_read(val) != 0);
 	finish_wait(wq_head, &wbq_entry->wq_entry);
 	return ret;
@@ -210,8 +210,9 @@ int __wait_on_atomic_t(struct wait_queue_head *wq_head, struct wait_bit_queue_en
 		},							\
 	}
 
-__sched int out_of_line_wait_on_atomic_t(atomic_t *p, int (*action)(atomic_t *),
-					 unsigned mode)
+__sched int out_of_line_wait_on_atomic_t(atomic_t *p,
+					 wait_atomic_t_action_f action,
+					 unsigned int mode)
 {
 	struct wait_queue_head *wq_head = atomic_t_waitqueue(p);
 	DEFINE_WAIT_ATOMIC_T(wq_entry, p);
@@ -220,6 +221,15 @@ __sched int out_of_line_wait_on_atomic_t(atomic_t *p, int (*action)(atomic_t *),
 }
 EXPORT_SYMBOL(out_of_line_wait_on_atomic_t);
 
+__sched int atomic_t_wait(atomic_t *counter, unsigned int mode)
+{
+	schedule();
+	if (signal_pending_state(mode, current))
+		return -EINTR;
+	return 0;
+}
+EXPORT_SYMBOL(atomic_t_wait);
+
 /**
  * wake_up_atomic_t - Wake up a waiter on a atomic_t
  * @p: The atomic_t being waited on, a kernel virtual address

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