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Date: Mon, 19 Aug 2024 15:20:41 +1000 Message-ID: <20240819053605.11706-8-neilb@suse.de> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240819053605.11706-1-neilb@suse.de> References: <20240819053605.11706-1-neilb@suse.de> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Level: X-Spam-Flag: NO X-Rspamd-Queue-Id: 549D71FE4D X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spamd-Result: default: False [-5.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; DWL_DNSWL_MED(-2.00)[suse.de:dkim]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; ARC_NA(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_COUNT_TWO(0.00)[2]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; RCPT_COUNT_FIVE(0.00)[5]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+] X-Spam-Score: -5.01 wake_up_bit() is a fragile interface. It requires a preceding barrier in most cased but often this barrier is forgotten by developers. There are three cases: 1/ in the common case the relevant bit has been cleared by an atomic operation such as clear_bit(). In this case smp_mb__after_atomic() is needed. This patch changes wake_up_bit() to include this barrier so that in the common case it works correctly. 2/ If the bit has been cleared by a non-atomic operation such as a simple bit mask and assignment, then a full barrier - smp_mb() - is needed. A new interface wake_up_bit_mb() is provided which provided this barrier and documents the expected use case. 3/ If a fully ordered operation such as test_and_clear_bit() is used to clear the bit then no barrier is needed. A new interface wake_up_bit_relaxed() is added which provides for this possibility. It is exactly the old wake_up_bit() function. This patch also removes all explicit barriers from before wake_up_bit(), changing some into wake_up_bit_mb() as required. It also changes some to wake_up_bit_relaxed() as well as removing the barrier - in cases where the barrier was never needed. Signed-off-by: NeilBrown --- drivers/bluetooth/btintel.h | 2 +- drivers/bluetooth/btmtk.c | 9 ++-- drivers/bluetooth/btmtksdio.c | 8 ++-- drivers/bluetooth/btmtkuart.c | 8 ++-- drivers/bluetooth/hci_intel.c | 8 ++-- drivers/bluetooth/hci_mrvl.c | 2 - drivers/md/dm-bufio.c | 4 -- drivers/md/dm-snap.c | 1 - drivers/md/dm-zoned-metadata.c | 2 - drivers/md/dm-zoned-reclaim.c | 1 - drivers/md/dm.c | 1 - drivers/media/usb/dvb-usb-v2/dvb_usb_core.c | 3 -- fs/btrfs/extent_io.c | 2 - fs/buffer.c | 1 - fs/ceph/dir.c | 2 +- fs/ceph/file.c | 4 +- fs/dcache.c | 3 +- fs/ext4/fast_commit.c | 6 +-- fs/fs-writeback.c | 4 +- fs/gfs2/glock.c | 2 - fs/gfs2/lock_dlm.c | 2 - fs/gfs2/recovery.c | 1 - fs/gfs2/sys.c | 1 - fs/gfs2/util.c | 1 - fs/inode.c | 8 ++-- fs/jbd2/commit.c | 7 +--- fs/nfs/inode.c | 1 - fs/nfs/pagelist.c | 2 - fs/nfs/pnfs.c | 5 +-- fs/nfsd/nfs4recover.c | 1 - fs/orangefs/file.c | 1 - fs/smb/client/inode.c | 1 - fs/smb/server/oplock.c | 2 - include/linux/wait_bit.h | 46 +++++++++++++++++++-- kernel/sched/wait_bit.c | 13 +++--- kernel/signal.c | 3 +- mm/ksm.c | 1 - net/bluetooth/hci_event.c | 5 +-- net/sunrpc/sched.c | 1 - security/keys/key.c | 4 +- 40 files changed, 80 insertions(+), 99 deletions(-) diff --git a/drivers/bluetooth/btintel.h b/drivers/bluetooth/btintel.h index aa70e4c27416..1271ded14f9a 100644 --- a/drivers/bluetooth/btintel.h +++ b/drivers/bluetooth/btintel.h @@ -202,7 +202,7 @@ struct btintel_data { #define btintel_wake_up_flag(hdev, nr) \ do { \ struct btintel_data *intel = hci_get_priv((hdev)); \ - wake_up_bit(intel->flags, (nr)); \ + wake_up_bit_relaxed(intel->flags, (nr)); \ } while (0) #define btintel_get_flag(hdev) \ diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c index 2b7c80043aa2..3bbb566bb1c0 100644 --- a/drivers/bluetooth/btmtk.c +++ b/drivers/bluetooth/btmtk.c @@ -482,12 +482,9 @@ static void btmtk_usb_wmt_recv(struct urb *urb) } if (test_and_clear_bit(BTMTK_TX_WAIT_VND_EVT, - &data->flags)) { - /* Barrier to sync with other CPUs */ - smp_mb__after_atomic(); - wake_up_bit(&data->flags, - BTMTK_TX_WAIT_VND_EVT); - } + &data->flags)) + wake_up_bit_relaxed(&data->flags, + BTMTK_TX_WAIT_VND_EVT); kfree(urb->setup_packet); return; } else if (urb->status == -ENOENT) { diff --git a/drivers/bluetooth/btmtksdio.c b/drivers/bluetooth/btmtksdio.c index 39d6898497a4..3fd84ae746c4 100644 --- a/drivers/bluetooth/btmtksdio.c +++ b/drivers/bluetooth/btmtksdio.c @@ -401,11 +401,9 @@ static int btmtksdio_recv_event(struct hci_dev *hdev, struct sk_buff *skb) if (evt == HCI_EV_WMT) { if (test_and_clear_bit(BTMTKSDIO_TX_WAIT_VND_EVT, - &bdev->tx_state)) { - /* Barrier to sync with other CPUs */ - smp_mb__after_atomic(); - wake_up_bit(&bdev->tx_state, BTMTKSDIO_TX_WAIT_VND_EVT); - } + &bdev->tx_state)) + wake_up_bit_relaxed(&bdev->tx_state, + BTMTKSDIO_TX_WAIT_VND_EVT); } return 0; diff --git a/drivers/bluetooth/btmtkuart.c b/drivers/bluetooth/btmtkuart.c index aa87c3e78871..b02b56d7d1b0 100644 --- a/drivers/bluetooth/btmtkuart.c +++ b/drivers/bluetooth/btmtkuart.c @@ -211,11 +211,9 @@ static int btmtkuart_recv_event(struct hci_dev *hdev, struct sk_buff *skb) if (hdr->evt == HCI_EV_WMT) { if (test_and_clear_bit(BTMTKUART_TX_WAIT_VND_EVT, - &bdev->tx_state)) { - /* Barrier to sync with other CPUs */ - smp_mb__after_atomic(); - wake_up_bit(&bdev->tx_state, BTMTKUART_TX_WAIT_VND_EVT); - } + &bdev->tx_state)) + wake_up_bit_relaxed(&bdev->tx_state, + BTMTKUART_TX_WAIT_VND_EVT); } return 0; diff --git a/drivers/bluetooth/hci_intel.c b/drivers/bluetooth/hci_intel.c index 999ccd5bb4f2..06ab03df9a7a 100644 --- a/drivers/bluetooth/hci_intel.c +++ b/drivers/bluetooth/hci_intel.c @@ -887,7 +887,7 @@ static int intel_recv_event(struct hci_dev *hdev, struct sk_buff *skb) if (test_and_clear_bit(STATE_DOWNLOADING, &intel->flags) && test_bit(STATE_FIRMWARE_LOADED, &intel->flags)) - wake_up_bit(&intel->flags, STATE_DOWNLOADING); + wake_up_bit_relaxed(&intel->flags, STATE_DOWNLOADING); /* When switching to the operational firmware the device * sends a vendor specific event indicating that the bootup @@ -896,7 +896,7 @@ static int intel_recv_event(struct hci_dev *hdev, struct sk_buff *skb) } else if (skb->len == 9 && hdr->evt == 0xff && hdr->plen == 0x07 && skb->data[2] == 0x02) { if (test_and_clear_bit(STATE_BOOTING, &intel->flags)) - wake_up_bit(&intel->flags, STATE_BOOTING); + wake_up_bit_relaxed(&intel->flags, STATE_BOOTING); } recv: return hci_recv_frame(hdev, skb); @@ -934,12 +934,12 @@ static int intel_recv_lpm(struct hci_dev *hdev, struct sk_buff *skb) case LPM_OP_SUSPEND_ACK: set_bit(STATE_SUSPENDED, &intel->flags); if (test_and_clear_bit(STATE_LPM_TRANSACTION, &intel->flags)) - wake_up_bit(&intel->flags, STATE_LPM_TRANSACTION); + wake_up_bit_relaxed(&intel->flags, STATE_LPM_TRANSACTION); break; case LPM_OP_RESUME_ACK: clear_bit(STATE_SUSPENDED, &intel->flags); if (test_and_clear_bit(STATE_LPM_TRANSACTION, &intel->flags)) - wake_up_bit(&intel->flags, STATE_LPM_TRANSACTION); + wake_up_bit_relaxed(&intel->flags, STATE_LPM_TRANSACTION); break; default: bt_dev_err(hdev, "Unknown LPM opcode (%02x)", lpm->opcode); diff --git a/drivers/bluetooth/hci_mrvl.c b/drivers/bluetooth/hci_mrvl.c index e08222395772..5486cf78a99b 100644 --- a/drivers/bluetooth/hci_mrvl.c +++ b/drivers/bluetooth/hci_mrvl.c @@ -184,7 +184,6 @@ static int mrvl_recv_fw_req(struct hci_dev *hdev, struct sk_buff *skb) mrvl->tx_len = le16_to_cpu(pkt->lhs); clear_bit(STATE_FW_REQ_PENDING, &mrvl->flags); - smp_mb__after_atomic(); wake_up_bit(&mrvl->flags, STATE_FW_REQ_PENDING); done: @@ -219,7 +218,6 @@ static int mrvl_recv_chip_ver(struct hci_dev *hdev, struct sk_buff *skb) bt_dev_info(hdev, "Controller id = %x, rev = %x", mrvl->id, mrvl->rev); clear_bit(STATE_CHIP_VER_PENDING, &mrvl->flags); - smp_mb__after_atomic(); wake_up_bit(&mrvl->flags, STATE_CHIP_VER_PENDING); done: diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index 098bf526136c..14b4d7cabbd6 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -1432,8 +1432,6 @@ static void write_endio(struct dm_buffer *b, blk_status_t status) smp_mb__before_atomic(); clear_bit(B_WRITING, &b->state); - smp_mb__after_atomic(); - wake_up_bit(&b->state, B_WRITING); } @@ -1843,8 +1841,6 @@ static void read_endio(struct dm_buffer *b, blk_status_t status) smp_mb__before_atomic(); clear_bit(B_READING, &b->state); - smp_mb__after_atomic(); - wake_up_bit(&b->state, B_READING); } diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index f40c18da4000..1549ab975021 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -921,7 +921,6 @@ static int init_hash_tables(struct dm_snapshot *s) static void merge_shutdown(struct dm_snapshot *s) { clear_bit_unlock(RUNNING_MERGE, &s->state_bits); - smp_mb__after_atomic(); wake_up_bit(&s->state_bits, RUNNING_MERGE); } diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c index 8156881a31de..7ea225ce418f 100644 --- a/drivers/md/dm-zoned-metadata.c +++ b/drivers/md/dm-zoned-metadata.c @@ -525,7 +525,6 @@ static void dmz_mblock_bio_end_io(struct bio *bio) flag = DMZ_META_READING; clear_bit_unlock(flag, &mblk->state); - smp_mb__after_atomic(); wake_up_bit(&mblk->state, flag); bio_put(bio); @@ -1917,7 +1916,6 @@ void dmz_unlock_zone_reclaim(struct dm_zone *zone) WARN_ON(!dmz_in_reclaim(zone)); clear_bit_unlock(DMZ_RECLAIM, &zone->flags); - smp_mb__after_atomic(); wake_up_bit(&zone->flags, DMZ_RECLAIM); } diff --git a/drivers/md/dm-zoned-reclaim.c b/drivers/md/dm-zoned-reclaim.c index d58db9a27e6c..9a7dadbb8eb7 100644 --- a/drivers/md/dm-zoned-reclaim.c +++ b/drivers/md/dm-zoned-reclaim.c @@ -107,7 +107,6 @@ static void dmz_reclaim_kcopy_end(int read_err, unsigned long write_err, zrc->kc_err = 0; clear_bit_unlock(DMZ_RECLAIM_KCOPY, &zrc->flags); - smp_mb__after_atomic(); wake_up_bit(&zrc->flags, DMZ_RECLAIM_KCOPY); } diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 97fab2087df8..3fd19d478f62 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -3154,7 +3154,6 @@ static void __dm_internal_resume(struct mapped_device *md) } done: clear_bit(DMF_SUSPENDED_INTERNALLY, &md->flags); - smp_mb__after_atomic(); wake_up_bit(&md->flags, DMF_SUSPENDED_INTERNALLY); } diff --git a/drivers/media/usb/dvb-usb-v2/dvb_usb_core.c b/drivers/media/usb/dvb-usb-v2/dvb_usb_core.c index f1c79f351ec8..7df6b0791ebd 100644 --- a/drivers/media/usb/dvb-usb-v2/dvb_usb_core.c +++ b/drivers/media/usb/dvb-usb-v2/dvb_usb_core.c @@ -376,7 +376,6 @@ static int dvb_usb_stop_feed(struct dvb_demux_feed *dvbdmxfeed) /* clear 'streaming' status bit */ clear_bit(ADAP_STREAMING, &adap->state_bits); - smp_mb__after_atomic(); wake_up_bit(&adap->state_bits, ADAP_STREAMING); skip_feed_stop: @@ -581,7 +580,6 @@ static int dvb_usb_fe_init(struct dvb_frontend *fe) err: if (!adap->suspend_resume_active) { clear_bit(ADAP_INIT, &adap->state_bits); - smp_mb__after_atomic(); wake_up_bit(&adap->state_bits, ADAP_INIT); } @@ -621,7 +619,6 @@ static int dvb_usb_fe_sleep(struct dvb_frontend *fe) if (!adap->suspend_resume_active) { adap->active_fe = -1; clear_bit(ADAP_SLEEP, &adap->state_bits); - smp_mb__after_atomic(); wake_up_bit(&adap->state_bits, ADAP_SLEEP); } diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index aa7f8148cd0d..0b9cb4c87adf 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -1762,7 +1762,6 @@ static void end_bbio_meta_write(struct btrfs_bio *bbio) } clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags); - smp_mb__after_atomic(); wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK); bio_put(&bbio->bio); @@ -3506,7 +3505,6 @@ void set_extent_buffer_uptodate(struct extent_buffer *eb) static void clear_extent_buffer_reading(struct extent_buffer *eb) { clear_bit(EXTENT_BUFFER_READING, &eb->bflags); - smp_mb__after_atomic(); wake_up_bit(&eb->bflags, EXTENT_BUFFER_READING); } diff --git a/fs/buffer.c b/fs/buffer.c index e55ad471c530..2932618c88e4 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -75,7 +75,6 @@ EXPORT_SYMBOL(__lock_buffer); void unlock_buffer(struct buffer_head *bh) { clear_bit_unlock(BH_Lock, &bh->b_state); - smp_mb__after_atomic(); wake_up_bit(&bh->b_state, BH_Lock); } EXPORT_SYMBOL(unlock_buffer); diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c index 18c72b305858..20d02142b059 100644 --- a/fs/ceph/dir.c +++ b/fs/ceph/dir.c @@ -1254,7 +1254,7 @@ static void ceph_async_unlink_cb(struct ceph_mds_client *mdsc, spin_lock(&dentry->d_lock); di->flags &= ~CEPH_DENTRY_ASYNC_UNLINK; - wake_up_bit(&di->flags, CEPH_DENTRY_ASYNC_UNLINK_BIT); + wake_up_bit_mb(&di->flags, CEPH_DENTRY_ASYNC_UNLINK_BIT); spin_unlock(&dentry->d_lock); synchronize_rcu(); diff --git a/fs/ceph/file.c b/fs/ceph/file.c index 4b8d59ebda00..d779780abea5 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -581,7 +581,7 @@ static void wake_async_create_waiters(struct inode *inode, spin_lock(&ci->i_ceph_lock); if (ci->i_ceph_flags & CEPH_I_ASYNC_CREATE) { ci->i_ceph_flags &= ~CEPH_I_ASYNC_CREATE; - wake_up_bit(&ci->i_ceph_flags, CEPH_ASYNC_CREATE_BIT); + wake_up_bit_mb(&ci->i_ceph_flags, CEPH_ASYNC_CREATE_BIT); if (ci->i_ceph_flags & CEPH_I_ASYNC_CHECK_CAPS) { ci->i_ceph_flags &= ~CEPH_I_ASYNC_CHECK_CAPS; @@ -766,7 +766,7 @@ static int ceph_finish_async_create(struct inode *dir, struct inode *inode, spin_lock(&dentry->d_lock); di->flags &= ~CEPH_DENTRY_ASYNC_CREATE; - wake_up_bit(&di->flags, CEPH_DENTRY_ASYNC_CREATE_BIT); + wake_up_bit_mb(&di->flags, CEPH_DENTRY_ASYNC_CREATE_BIT); spin_unlock(&dentry->d_lock); return ret; diff --git a/fs/dcache.c b/fs/dcache.c index 3d8daaecb6d1..8f63de904d7c 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1908,8 +1908,7 @@ void d_instantiate_new(struct dentry *entry, struct inode *inode) __d_instantiate(entry, inode); WARN_ON(!(inode->i_state & I_NEW)); inode->i_state &= ~I_NEW & ~I_CREATING; - smp_mb(); - wake_up_bit(&inode->i_state, __I_NEW); + wake_up_bit_mb(&inode->i_state, __I_NEW); spin_unlock(&inode->i_lock); } EXPORT_SYMBOL(d_instantiate_new); diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c index 3926a05eceee..03d94f5fc8c8 100644 --- a/fs/ext4/fast_commit.c +++ b/fs/ext4/fast_commit.c @@ -1290,12 +1290,10 @@ static void ext4_fc_cleanup(journal_t *journal, int full, tid_t tid) EXT4_STATE_FC_COMMITTING); if (tid_geq(tid, iter->i_sync_tid)) ext4_fc_reset_inode(&iter->vfs_inode); - /* Make sure EXT4_STATE_FC_COMMITTING bit is clear */ - smp_mb(); #if (BITS_PER_LONG < 64) - wake_up_bit(&iter->i_state_flags, EXT4_STATE_FC_COMMITTING); + wake_up_bit_mb(&iter->i_state_flags, EXT4_STATE_FC_COMMITTING); #else - wake_up_bit(&iter->i_flags, EXT4_STATE_FC_COMMITTING); + wake_up_bit_mb(&iter->i_flags, EXT4_STATE_FC_COMMITTING); #endif } diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index b865a3fa52f3..0f6646d67a73 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1384,9 +1384,7 @@ static void inode_sync_complete(struct inode *inode) inode->i_state &= ~I_SYNC; /* If inode is clean an unused, put it into LRU now... */ inode_add_lru(inode); - /* Waiters must see I_SYNC cleared before being woken up */ - smp_mb(); - wake_up_bit(&inode->i_state, __I_SYNC); + wake_up_bit_mb(&inode->i_state, __I_SYNC); } static bool inode_dirtied_after(struct inode *inode, unsigned long t) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 12a769077ea0..e1afe9aa7c2a 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -380,7 +380,6 @@ static inline bool may_grant(struct gfs2_glock *gl, static void gfs2_holder_wake(struct gfs2_holder *gh) { clear_bit(HIF_WAIT, &gh->gh_iflags); - smp_mb__after_atomic(); wake_up_bit(&gh->gh_iflags, HIF_WAIT); if (gh->gh_flags & GL_ASYNC) { struct gfs2_sbd *sdp = gh->gh_gl->gl_name.ln_sbd; @@ -576,7 +575,6 @@ static void gfs2_demote_wake(struct gfs2_glock *gl) { gl->gl_demote_state = LM_ST_EXCLUSIVE; clear_bit(GLF_DEMOTE, &gl->gl_flags); - smp_mb__after_atomic(); wake_up_bit(&gl->gl_flags, GLF_DEMOTE); } diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c index fa5134df985f..921b26b96192 100644 --- a/fs/gfs2/lock_dlm.c +++ b/fs/gfs2/lock_dlm.c @@ -1224,7 +1224,6 @@ static void gdlm_recover_done(void *arg, struct dlm_slot *slots, int num_slots, queue_delayed_work(gfs2_control_wq, &sdp->sd_control_work, 0); clear_bit(DFL_DLM_RECOVERY, &ls->ls_recover_flags); - smp_mb__after_atomic(); wake_up_bit(&ls->ls_recover_flags, DFL_DLM_RECOVERY); spin_unlock(&ls->ls_recover_spin); } @@ -1366,7 +1365,6 @@ static int gdlm_mount(struct gfs2_sbd *sdp, const char *table) ls->ls_first = !!test_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags); clear_bit(SDF_NOJOURNALID, &sdp->sd_flags); - smp_mb__after_atomic(); wake_up_bit(&sdp->sd_flags, SDF_NOJOURNALID); return 0; diff --git a/fs/gfs2/recovery.c b/fs/gfs2/recovery.c index f4fe7039f725..e70cf003d524 100644 --- a/fs/gfs2/recovery.c +++ b/fs/gfs2/recovery.c @@ -558,7 +558,6 @@ void gfs2_recover_func(struct work_struct *work) gfs2_recovery_done(sdp, jd->jd_jid, LM_RD_GAVEUP); done: clear_bit(JDF_RECOVERY, &jd->jd_flags); - smp_mb__after_atomic(); wake_up_bit(&jd->jd_flags, JDF_RECOVERY); } diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c index ecc699f8d9fc..738337e35724 100644 --- a/fs/gfs2/sys.c +++ b/fs/gfs2/sys.c @@ -587,7 +587,6 @@ static ssize_t jid_store(struct gfs2_sbd *sdp, const char *buf, size_t len) rv = jid = -EINVAL; sdp->sd_lockstruct.ls_jid = jid; clear_bit(SDF_NOJOURNALID, &sdp->sd_flags); - smp_mb__after_atomic(); wake_up_bit(&sdp->sd_flags, SDF_NOJOURNALID); out: spin_unlock(&sdp->sd_jindex_spin); diff --git a/fs/gfs2/util.c b/fs/gfs2/util.c index 13be8d1d228b..2818f3891498 100644 --- a/fs/gfs2/util.c +++ b/fs/gfs2/util.c @@ -353,7 +353,6 @@ int gfs2_withdraw(struct gfs2_sbd *sdp) fs_err(sdp, "File system withdrawn\n"); dump_stack(); clear_bit(SDF_WITHDRAW_IN_PROG, &sdp->sd_flags); - smp_mb__after_atomic(); wake_up_bit(&sdp->sd_flags, SDF_WITHDRAW_IN_PROG); } diff --git a/fs/inode.c b/fs/inode.c index 91bb2f80fa03..f5f35b701196 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -687,7 +687,7 @@ static void evict(struct inode *inode) * used as an indicator whether blocking on it is safe. */ spin_lock(&inode->i_lock); - wake_up_bit(&inode->i_state, __I_NEW); + wake_up_bit_relaxed(&inode->i_state, __I_NEW); BUG_ON(inode->i_state != (I_FREEING | I_CLEAR)); spin_unlock(&inode->i_lock); @@ -1095,8 +1095,7 @@ void unlock_new_inode(struct inode *inode) spin_lock(&inode->i_lock); WARN_ON(!(inode->i_state & I_NEW)); inode->i_state &= ~I_NEW & ~I_CREATING; - smp_mb(); - wake_up_bit(&inode->i_state, __I_NEW); + wake_up_bit_mb(&inode->i_state, __I_NEW); spin_unlock(&inode->i_lock); } EXPORT_SYMBOL(unlock_new_inode); @@ -1107,8 +1106,7 @@ void discard_new_inode(struct inode *inode) spin_lock(&inode->i_lock); WARN_ON(!(inode->i_state & I_NEW)); inode->i_state &= ~I_NEW; - smp_mb(); - wake_up_bit(&inode->i_state, __I_NEW); + wake_up_bit_mb(&inode->i_state, __I_NEW); spin_unlock(&inode->i_lock); iput(inode); } diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index 4305a1ac808a..55ba3f62fbe3 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -40,7 +40,6 @@ static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate) clear_buffer_uptodate(bh); if (orig_bh) { clear_bit_unlock(BH_Shadow, &orig_bh->b_state); - smp_mb__after_atomic(); wake_up_bit(&orig_bh->b_state, BH_Shadow); } unlock_buffer(bh); @@ -230,8 +229,7 @@ static int journal_submit_data_buffers(journal_t *journal, spin_lock(&journal->j_list_lock); J_ASSERT(jinode->i_transaction == commit_transaction); jinode->i_flags &= ~JI_COMMIT_RUNNING; - smp_mb(); - wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING); + wake_up_bit_mb(&jinode->i_flags, __JI_COMMIT_RUNNING); } spin_unlock(&journal->j_list_lock); return ret; @@ -273,8 +271,7 @@ static int journal_finish_inode_data_buffers(journal_t *journal, cond_resched(); spin_lock(&journal->j_list_lock); jinode->i_flags &= ~JI_COMMIT_RUNNING; - smp_mb(); - wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING); + wake_up_bit_mb(&jinode->i_flags, __JI_COMMIT_RUNNING); } /* Now refile inode to proper lists */ diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index b4914a11c3c2..19d175446899 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -1429,7 +1429,6 @@ int nfs_clear_invalid_mapping(struct address_space *mapping) trace_nfs_invalidate_mapping_exit(inode, ret); clear_bit_unlock(NFS_INO_INVALIDATING, bitlock); - smp_mb__after_atomic(); wake_up_bit(bitlock, NFS_INO_INVALIDATING); out: return ret; diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c index 8ae767578cd9..9f45c08d2e79 100644 --- a/fs/nfs/pagelist.c +++ b/fs/nfs/pagelist.c @@ -215,7 +215,6 @@ void nfs_page_clear_headlock(struct nfs_page *req) { clear_bit_unlock(PG_HEADLOCK, &req->wb_flags); - smp_mb__after_atomic(); if (!test_bit(PG_CONTENDED1, &req->wb_flags)) return; wake_up_bit(&req->wb_flags, PG_HEADLOCK); @@ -520,7 +519,6 @@ nfs_create_subreq(struct nfs_page *req, void nfs_unlock_request(struct nfs_page *req) { clear_bit_unlock(PG_BUSY, &req->wb_flags); - smp_mb__after_atomic(); if (!test_bit(PG_CONTENDED2, &req->wb_flags)) return; wake_up_bit(&req->wb_flags, PG_BUSY); diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index aa698481bec8..877fc154eb2b 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -388,7 +388,6 @@ static void pnfs_clear_layoutreturn_waitbit(struct pnfs_layout_hdr *lo) { clear_bit_unlock(NFS_LAYOUT_RETURN, &lo->plh_flags); clear_bit(NFS_LAYOUT_RETURN_LOCK, &lo->plh_flags); - smp_mb__after_atomic(); wake_up_bit(&lo->plh_flags, NFS_LAYOUT_RETURN); rpc_wake_up(&NFS_SERVER(lo->plh_inode)->roc_rpcwaitq); } @@ -2044,7 +2043,7 @@ static void nfs_layoutget_end(struct pnfs_layout_hdr *lo) { if (atomic_dec_and_test(&lo->plh_outstanding) && test_and_clear_bit(NFS_LAYOUT_DRAIN, &lo->plh_flags)) - wake_up_bit(&lo->plh_flags, NFS_LAYOUT_DRAIN); + wake_up_bit_relaxed(&lo->plh_flags, NFS_LAYOUT_DRAIN); } static bool pnfs_is_first_layoutget(struct pnfs_layout_hdr *lo) @@ -2057,7 +2056,6 @@ static void pnfs_clear_first_layoutget(struct pnfs_layout_hdr *lo) unsigned long *bitlock = &lo->plh_flags; clear_bit_unlock(NFS_LAYOUT_FIRST_LAYOUTGET, bitlock); - smp_mb__after_atomic(); wake_up_bit(bitlock, NFS_LAYOUT_FIRST_LAYOUTGET); } @@ -3230,7 +3228,6 @@ static void pnfs_clear_layoutcommitting(struct inode *inode) unsigned long *bitlock = &NFS_I(inode)->flags; clear_bit_unlock(NFS_INO_LAYOUTCOMMITTING, bitlock); - smp_mb__after_atomic(); wake_up_bit(bitlock, NFS_INO_LAYOUTCOMMITTING); } diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c index 67d8673a9391..3e1a434bc649 100644 --- a/fs/nfsd/nfs4recover.c +++ b/fs/nfsd/nfs4recover.c @@ -1897,7 +1897,6 @@ nfsd4_cltrack_upcall_unlock(struct nfs4_client *clp) { smp_mb__before_atomic(); clear_bit(NFSD4_CLIENT_UPCALL_LOCK, &clp->cl_flags); - smp_mb__after_atomic(); wake_up_bit(&clp->cl_flags, NFSD4_CLIENT_UPCALL_LOCK); } diff --git a/fs/orangefs/file.c b/fs/orangefs/file.c index d68372241b30..d620b56a1002 100644 --- a/fs/orangefs/file.c +++ b/fs/orangefs/file.c @@ -314,7 +314,6 @@ int orangefs_revalidate_mapping(struct inode *inode) orangefs_cache_timeout_msecs*HZ/1000; clear_bit(1, bitlock); - smp_mb__after_atomic(); wake_up_bit(bitlock, 1); return ret; diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c index dd0afa23734c..8da74f15cc95 100644 --- a/fs/smb/client/inode.c +++ b/fs/smb/client/inode.c @@ -2511,7 +2511,6 @@ cifs_revalidate_mapping(struct inode *inode) skip_invalidate: clear_bit_unlock(CIFS_INO_LOCK, flags); - smp_mb__after_atomic(); wake_up_bit(flags, CIFS_INO_LOCK); return rc; diff --git a/fs/smb/server/oplock.c b/fs/smb/server/oplock.c index a8f52c4ebbda..b039b242df46 100644 --- a/fs/smb/server/oplock.c +++ b/fs/smb/server/oplock.c @@ -594,8 +594,6 @@ static void wait_for_break_ack(struct oplock_info *opinfo) static void wake_up_oplock_break(struct oplock_info *opinfo) { clear_bit_unlock(0, &opinfo->pending_break); - /* memory barrier is needed for wake_up_bit() */ - smp_mb__after_atomic(); wake_up_bit(&opinfo->pending_break, 0); } diff --git a/include/linux/wait_bit.h b/include/linux/wait_bit.h index 178ed8bed91c..609c10fcd344 100644 --- a/include/linux/wait_bit.h +++ b/include/linux/wait_bit.h @@ -26,7 +26,7 @@ typedef int wait_bit_action_f(struct wait_bit_key *key, 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); -void wake_up_bit(void *word, int bit); +void wake_up_bit_relaxed(void *word, int bit); 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); @@ -318,6 +318,48 @@ do { \ __ret; \ }) +/** + * wake_up_bit - wake up waiters on a bit + * @word: the word being waited on, a kernel virtual address + * @bit: the bit of the word being waited on + * + * There is a standard hashed waitqueue table for generic use. This + * is the part of the hash-table's accessor API that wakes up waiters + * on a bit. For instance, if one were to have waiters on a bitflag, + * one would call wake_up_bit() after atomically clearing the bit. + * + * This interface should only be use when the bit is cleared atomically, + * such as with clear_bit(), atomic_andnot(), code inside a locked + * region (with this interface called after the unlock). If this + * bit is cleared non-atomically, wake_up_bit_mb() should be used. + */ +static inline void wake_up_bit(void *word, int bit) +{ + smp_mb__after_atomic(); + wake_up_bit_relaxed(word, bit); +} + +/** + * wake_up_bit_mb - wake up waiters on a bit with full barrier + * @word: the word being waited on, a kernel virtual address + * @bit: the bit of the word being waited on + * + * There is a standard hashed waitqueue table for generic use. This + * is the part of the hash-table's accessor API that wakes up waiters + * on a bit. For instance, if one were to have waiters on a bitflag, + * one would call wake_up_bit() after non-atomically clearing the bit. + * + * This interface has a full barrier and so is safe to use anywhere. + * It is particular intended for use after the bit has been cleared + * (or set) non-atmomically with simple assignment. Where the bit + * it cleared atomically, the barrier used may be excessively. + */ +static inline void wake_up_bit_mb(void *word, int bit) +{ + smp_mb(); + wake_up_bit_relaxed(word, bit); +} + /** * clear_and_wake_up_bit - clear a bit and wake up anyone waiting on that bit * @@ -330,8 +372,6 @@ do { \ static inline void clear_and_wake_up_bit(int bit, void *word) { clear_bit_unlock(bit, word); - /* See wake_up_bit() for which memory barrier you need to use. */ - smp_mb__after_atomic(); wake_up_bit(word, bit); } diff --git a/kernel/sched/wait_bit.c b/kernel/sched/wait_bit.c index 134d7112ef71..51d923bf207e 100644 --- a/kernel/sched/wait_bit.c +++ b/kernel/sched/wait_bit.c @@ -128,7 +128,7 @@ void __wake_up_bit(struct wait_queue_head *wq_head, void *word, int bit) EXPORT_SYMBOL(__wake_up_bit); /** - * wake_up_bit - wake up a waiter on a bit + * wake_up_bit_relaxed - wake up waiters on a bit * @word: the word being waited on, a kernel virtual address * @bit: the bit of the word being waited on * @@ -139,16 +139,15 @@ EXPORT_SYMBOL(__wake_up_bit); * * In order for this to function properly, as it uses waitqueue_active() * internally, some kind of memory barrier must be done prior to calling - * this. Typically, this will be smp_mb__after_atomic(), but in some - * cases where bitflags are manipulated non-atomically under a lock, one - * may need to use a less regular barrier, such fs/inode.c's smp_mb(), - * because spin_unlock() does not guarantee a memory barrier. + * this. Typically this will be provided implicitly by test_and_clear_bit(). + * If the bit is cleared without full ordering, an alternate interface + * such as wake_up_bit_mb() or wake_up_bit() should be used. */ -void wake_up_bit(void *word, int bit) +void wake_up_bit_relaxed(void *word, int bit) { __wake_up_bit(bit_waitqueue(word, bit), word, bit); } -EXPORT_SYMBOL(wake_up_bit); +EXPORT_SYMBOL(wake_up_bit_relaxed); wait_queue_head_t *__var_waitqueue(void *p) { diff --git a/kernel/signal.c b/kernel/signal.c index 60c737e423a1..1c3d51027cd0 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -306,8 +306,7 @@ void task_clear_jobctl_trapping(struct task_struct *task) { if (unlikely(task->jobctl & JOBCTL_TRAPPING)) { task->jobctl &= ~JOBCTL_TRAPPING; - smp_mb(); /* advised by wake_up_bit() */ - wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT); + wake_up_bit_mb(&task->jobctl, JOBCTL_TRAPPING_BIT); } } diff --git a/mm/ksm.c b/mm/ksm.c index 14d9e53b1ec2..edc55ba641fb 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -3267,7 +3267,6 @@ static int ksm_memory_callback(struct notifier_block *self, ksm_run &= ~KSM_RUN_OFFLINE; mutex_unlock(&ksm_thread_mutex); - smp_mb(); /* wake_up_bit advises this */ wake_up_bit(&ksm_run, ilog2(KSM_RUN_OFFLINE)); break; } diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c index d0c118c47f6c..226b37017d56 100644 --- a/net/bluetooth/hci_event.c +++ b/net/bluetooth/hci_event.c @@ -105,7 +105,6 @@ static u8 hci_cc_inquiry_cancel(struct hci_dev *hdev, void *data, return rp->status; clear_bit(HCI_INQUIRY, &hdev->flags); - smp_mb__after_atomic(); /* wake_up_bit advises about this barrier */ wake_up_bit(&hdev->flags, HCI_INQUIRY); hci_dev_lock(hdev); @@ -2972,9 +2971,7 @@ static void hci_inquiry_complete_evt(struct hci_dev *hdev, void *data, if (!test_and_clear_bit(HCI_INQUIRY, &hdev->flags)) return; - - smp_mb__after_atomic(); /* wake_up_bit advises about this barrier */ - wake_up_bit(&hdev->flags, HCI_INQUIRY); + wake_up_bit_relaxed(&hdev->flags, HCI_INQUIRY); if (!hci_dev_test_flag(hdev, HCI_MGMT)) return; diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index cef623ea1506..1f64652cb629 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -370,7 +370,6 @@ static void rpc_make_runnable(struct workqueue_struct *wq, INIT_WORK(&task->u.tk_work, rpc_async_schedule); queue_work(wq, &task->u.tk_work); } else { - smp_mb__after_atomic(); wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED); } } diff --git a/security/keys/key.c b/security/keys/key.c index 3d7d185019d3..8f7380935eb5 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -474,7 +474,7 @@ static int __key_instantiate_and_link(struct key *key, /* wake up anyone waiting for a key to be constructed */ if (awaken) - wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); + wake_up_bit_relaxed(&key->flags, KEY_FLAG_USER_CONSTRUCT); return ret; } @@ -629,7 +629,7 @@ int key_reject_and_link(struct key *key, /* wake up anyone waiting for a key to be constructed */ if (awaken) - wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); + wake_up_bit_relaxed(&key->flags, KEY_FLAG_USER_CONSTRUCT); return ret == 0 ? link_ret : ret; }