From 9fcbbac5ded489c3a4e121343db999dd51cd6c75 Mon Sep 17 00:00:00 2001 From: David Fries Date: Wed, 15 Jan 2014 22:29:18 -0600 Subject: w1: process w1 netlink commands in w1_process thread Netlink is a socket interface and is expected to be asynchronous. Clients can now make w1 requests without blocking by making use of the w1_master thread to process netlink commands which was previously only used for doing an automatic bus search. Signed-off-by: David Fries Acked-by: Evgeniy Polyakov Signed-off-by: Greg Kroah-Hartman --- drivers/w1/w1.c | 180 ++++++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 128 insertions(+), 52 deletions(-) (limited to 'drivers/w1/w1.c') diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c index 97b35cb8b6da..53846c7f24ff 100644 --- a/drivers/w1/w1.c +++ b/drivers/w1/w1.c @@ -79,19 +79,10 @@ static void w1_slave_release(struct device *dev) { struct w1_slave *sl = dev_to_w1_slave(dev); - dev_dbg(dev, "%s: Releasing %s.\n", __func__, sl->name); - - while (atomic_read(&sl->refcnt)) { - dev_dbg(dev, "Waiting for %s to become free: refcnt=%d.\n", - sl->name, atomic_read(&sl->refcnt)); - if (msleep_interruptible(1000)) - flush_signals(current); - } + dev_dbg(dev, "%s: Releasing %s [%p]\n", __func__, sl->name, sl); w1_family_put(sl->family); sl->master->slave_count--; - - complete(&sl->released); } static ssize_t name_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -277,7 +268,6 @@ static ssize_t w1_master_attribute_store_pullup(struct device *dev, mutex_lock(&md->mutex); md->enable_pullup = tmp; mutex_unlock(&md->mutex); - wake_up_process(md->thread); return count; } @@ -370,23 +360,20 @@ static ssize_t w1_master_attribute_show_slaves(struct device *dev, { struct w1_master *md = dev_to_w1_master(dev); int c = PAGE_SIZE; + struct list_head *ent, *n; + struct w1_slave *sl = NULL; - mutex_lock(&md->mutex); - - if (md->slave_count == 0) - c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n"); - else { - struct list_head *ent, *n; - struct w1_slave *sl; + mutex_lock(&md->list_mutex); - list_for_each_safe(ent, n, &md->slist) { - sl = list_entry(ent, struct w1_slave, w1_slave_entry); + list_for_each_safe(ent, n, &md->slist) { + sl = list_entry(ent, struct w1_slave, w1_slave_entry); - c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name); - } + c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name); } + if (!sl) + c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n"); - mutex_unlock(&md->mutex); + mutex_unlock(&md->list_mutex); return PAGE_SIZE - c; } @@ -440,19 +427,22 @@ static int w1_atoreg_num(struct device *dev, const char *buf, size_t count, } /* Searches the slaves in the w1_master and returns a pointer or NULL. - * Note: must hold the mutex + * Note: must not hold list_mutex */ struct w1_slave *w1_slave_search_device(struct w1_master *dev, struct w1_reg_num *rn) { struct w1_slave *sl; + mutex_lock(&dev->list_mutex); list_for_each_entry(sl, &dev->slist, w1_slave_entry) { if (sl->reg_num.family == rn->family && sl->reg_num.id == rn->id && sl->reg_num.crc == rn->crc) { + mutex_unlock(&dev->list_mutex); return sl; } } + mutex_unlock(&dev->list_mutex); return NULL; } @@ -509,7 +499,10 @@ static ssize_t w1_master_attribute_store_remove(struct device *dev, mutex_lock(&md->mutex); sl = w1_slave_search_device(md, &rn); if (sl) { - w1_slave_detach(sl); + result = w1_slave_detach(sl); + /* refcnt 0 means it was detached in the call */ + if (result == 0) + result = count; } else { dev_info(dev, "Device %02x-%012llx doesn't exists\n", rn.family, (unsigned long long)rn.id); @@ -704,7 +697,9 @@ static int __w1_attach_slave_device(struct w1_slave *sl) dev_set_uevent_suppress(&sl->dev, false); kobject_uevent(&sl->dev.kobj, KOBJ_ADD); + mutex_lock(&sl->master->list_mutex); list_add_tail(&sl->w1_slave_entry, &sl->master->slist); + mutex_unlock(&sl->master->list_mutex); return 0; } @@ -731,8 +726,8 @@ int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn) memset(&msg, 0, sizeof(msg)); memcpy(&sl->reg_num, rn, sizeof(sl->reg_num)); - atomic_set(&sl->refcnt, 0); - init_completion(&sl->released); + atomic_set(&sl->refcnt, 1); + atomic_inc(&sl->master->refcnt); /* slave modules need to be loaded in a context with unlocked mutex */ mutex_unlock(&dev->mutex); @@ -772,23 +767,48 @@ int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn) return 0; } -void w1_slave_detach(struct w1_slave *sl) +int w1_unref_slave(struct w1_slave *sl) { - struct w1_netlink_msg msg; - - dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl); - - list_del(&sl->w1_slave_entry); - - memset(&msg, 0, sizeof(msg)); - memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id)); - msg.type = W1_SLAVE_REMOVE; - w1_netlink_send(sl->master, &msg); - - device_unregister(&sl->dev); + struct w1_master *dev = sl->master; + int refcnt; + mutex_lock(&dev->list_mutex); + refcnt = atomic_sub_return(1, &sl->refcnt); + if (refcnt == 0) { + struct w1_netlink_msg msg; + + dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, + sl->name, sl); + + list_del(&sl->w1_slave_entry); + + memset(&msg, 0, sizeof(msg)); + memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id)); + msg.type = W1_SLAVE_REMOVE; + w1_netlink_send(sl->master, &msg); + + device_unregister(&sl->dev); + #ifdef DEBUG + memset(sl, 0, sizeof(*sl)); + #endif + kfree(sl); + } + atomic_dec(&dev->refcnt); + mutex_unlock(&dev->list_mutex); + return refcnt; +} - wait_for_completion(&sl->released); - kfree(sl); +int w1_slave_detach(struct w1_slave *sl) +{ + /* Only detach a slave once as it decreases the refcnt each time. */ + int destroy_now; + mutex_lock(&sl->master->list_mutex); + destroy_now = !test_bit(W1_SLAVE_DETACH, &sl->flags); + set_bit(W1_SLAVE_DETACH, &sl->flags); + mutex_unlock(&sl->master->list_mutex); + + if (destroy_now) + destroy_now = !w1_unref_slave(sl); + return destroy_now ? 0 : -EBUSY; } struct w1_master *w1_search_master_id(u32 id) @@ -817,7 +837,7 @@ struct w1_slave *w1_search_slave(struct w1_reg_num *id) mutex_lock(&w1_mlock); list_for_each_entry(dev, &w1_masters, w1_master_entry) { - mutex_lock(&dev->mutex); + mutex_lock(&dev->list_mutex); list_for_each_entry(sl, &dev->slist, w1_slave_entry) { if (sl->reg_num.family == id->family && sl->reg_num.id == id->id && @@ -828,7 +848,7 @@ struct w1_slave *w1_search_slave(struct w1_reg_num *id) break; } } - mutex_unlock(&dev->mutex); + mutex_unlock(&dev->list_mutex); if (found) break; @@ -848,6 +868,7 @@ void w1_reconnect_slaves(struct w1_family *f, int attach) dev_dbg(&dev->dev, "Reconnecting slaves in device %s " "for family %02x.\n", dev->name, f->fid); mutex_lock(&dev->mutex); + mutex_lock(&dev->list_mutex); list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) { /* If it is a new family, slaves with the default * family driver and are that family will be @@ -859,14 +880,19 @@ void w1_reconnect_slaves(struct w1_family *f, int attach) (!attach && sl->family->fid == f->fid)) { struct w1_reg_num rn; + mutex_unlock(&dev->list_mutex); memcpy(&rn, &sl->reg_num, sizeof(rn)); - w1_slave_detach(sl); - - w1_attach_slave_device(dev, &rn); + /* If it was already in use let the automatic + * scan pick it up again later. + */ + if (!w1_slave_detach(sl)) + w1_attach_slave_device(dev, &rn); + mutex_lock(&dev->list_mutex); } } dev_dbg(&dev->dev, "Reconnecting slaves in device %s " "has been finished.\n", dev->name); + mutex_unlock(&dev->list_mutex); mutex_unlock(&dev->mutex); } mutex_unlock(&w1_mlock); @@ -1020,17 +1046,24 @@ void w1_search_process_cb(struct w1_master *dev, u8 search_type, { struct w1_slave *sl, *sln; + mutex_lock(&dev->list_mutex); list_for_each_entry(sl, &dev->slist, w1_slave_entry) clear_bit(W1_SLAVE_ACTIVE, &sl->flags); + mutex_unlock(&dev->list_mutex); w1_search_devices(dev, search_type, cb); + mutex_lock(&dev->list_mutex); list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) { - if (!test_bit(W1_SLAVE_ACTIVE, &sl->flags) && !--sl->ttl) + if (!test_bit(W1_SLAVE_ACTIVE, &sl->flags) && !--sl->ttl) { + mutex_unlock(&dev->list_mutex); w1_slave_detach(sl); + mutex_lock(&dev->list_mutex); + } else if (test_bit(W1_SLAVE_ACTIVE, &sl->flags)) sl->ttl = dev->slave_ttl; } + mutex_unlock(&dev->list_mutex); if (dev->search_count > 0) dev->search_count--; @@ -1041,6 +1074,26 @@ static void w1_search_process(struct w1_master *dev, u8 search_type) w1_search_process_cb(dev, search_type, w1_slave_found); } +int w1_process_callbacks(struct w1_master *dev) +{ + int ret = 0; + struct w1_async_cmd *async_cmd, *async_n; + + /* The list can be added to in another thread, loop until it is empty */ + while (!list_empty(&dev->async_list)) { + list_for_each_entry_safe(async_cmd, async_n, &dev->async_list, + async_entry) { + /* drop the lock, if it is a search it can take a long + * time */ + mutex_unlock(&dev->list_mutex); + async_cmd->cb(dev, async_cmd); + ret = 1; + mutex_lock(&dev->list_mutex); + } + } + return ret; +} + int w1_process(void *data) { struct w1_master *dev = (struct w1_master *) data; @@ -1048,23 +1101,46 @@ int w1_process(void *data) * time can be calculated in jiffies once. */ const unsigned long jtime = msecs_to_jiffies(w1_timeout * 1000); + /* remainder if it woke up early */ + unsigned long jremain = 0; - while (!kthread_should_stop()) { - if (dev->search_count) { + for (;;) { + + if (!jremain && dev->search_count) { mutex_lock(&dev->mutex); w1_search_process(dev, W1_SEARCH); mutex_unlock(&dev->mutex); } + mutex_lock(&dev->list_mutex); + /* Note, w1_process_callback drops the lock while processing, + * but locks it again before returning. + */ + if (!w1_process_callbacks(dev) && jremain) { + /* a wake up is either to stop the thread, process + * callbacks, or search, it isn't process callbacks, so + * schedule a search. + */ + jremain = 1; + } + try_to_freeze(); __set_current_state(TASK_INTERRUPTIBLE); + /* hold list_mutex until after interruptible to prevent loosing + * the wakeup signal when async_cmd is added. + */ + mutex_unlock(&dev->list_mutex); + if (kthread_should_stop()) break; /* Only sleep when the search is active. */ - if (dev->search_count) - schedule_timeout(jtime); + if (dev->search_count) { + if (!jremain) + jremain = jtime; + jremain = schedule_timeout(jremain); + } else schedule(); } -- cgit v1.2.3