pcmcia: use pccardd to handle eject, insert, suspend and resume requests

This avoids any sysfs-related deadlock (or lockdep warning), such
as reported at http://lkml.org/lkml/2010/1/17/88 .

Reported-by: Ming Lei <tom.leiming@gmail.com>
Tested-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

5 files changed, 83 insertions, 141 deletions

diff --git a/drivers/pcmcia/cs.c b/drivers/pcmcia/cs.c
index 7ba45b0cca6b..823ecda32216 100644
--- a/drivers/pcmcia/cs.c
+++ b/drivers/pcmcia/cs.c
@@ -505,7 +505,10 @@ static int socket_insert(struct pcmcia_socket *skt)
         dev_dbg(&skt->dev, "insert\n");
 
         mutex_lock(&skt->ops_mutex);
-        WARN_ON(skt->state & SOCKET_INUSE);
+        if (skt->state & SOCKET_INUSE) {
+                mutex_unlock(&skt->ops_mutex);
+                return -EINVAL;
+        }
         skt->state |= SOCKET_INUSE;
 
         ret = socket_setup(skt, setup_delay);
@@ -682,16 +685,19 @@ static int pccardd(void *__skt)
         for (;;) {
                 unsigned long flags;
                 unsigned int events;
+                unsigned int sysfs_events;
 
                 set_current_state(TASK_INTERRUPTIBLE);
 
                 spin_lock_irqsave(&skt->thread_lock, flags);
                 events = skt->thread_events;
                 skt->thread_events = 0;
+                sysfs_events = skt->sysfs_events;
+                skt->sysfs_events = 0;
                 spin_unlock_irqrestore(&skt->thread_lock, flags);
 
+                mutex_lock(&skt->skt_mutex);
                 if (events) {
-                        mutex_lock(&skt->skt_mutex);
                         if (events & SS_DETECT)
                                 socket_detect_change(skt);
                         if (events & SS_BATDEAD)
@@ -700,10 +706,34 @@ static int pccardd(void *__skt)
                                 send_event(skt, CS_EVENT_BATTERY_LOW, CS_EVENT_PRI_LOW);
                         if (events & SS_READY)
                                 send_event(skt, CS_EVENT_READY_CHANGE, CS_EVENT_PRI_LOW);
-                        mutex_unlock(&skt->skt_mutex);
-                        continue;
                 }
 
+                if (sysfs_events) {
+                        if (sysfs_events & PCMCIA_UEVENT_EJECT)
+                                socket_remove(skt);
+                        if (sysfs_events & PCMCIA_UEVENT_INSERT)
+                                socket_insert(skt);
+                        if ((sysfs_events & PCMCIA_UEVENT_RESUME) &&
+                                !(skt->state & SOCKET_CARDBUS)) {
+                                ret = socket_resume(skt);
+                                if (!ret && skt->callback)
+                                        skt->callback->resume(skt);
+                        }
+                        if ((sysfs_events & PCMCIA_UEVENT_SUSPEND) &&
+                                !(skt->state & SOCKET_CARDBUS)) {
+                                if (skt->callback)
+                                        ret = skt->callback->suspend(skt);
+                                else
+                                        ret = 0;
+                                if (!ret)
+                                        socket_suspend(skt);
+                        }
+                }
+                mutex_unlock(&skt->skt_mutex);
+
+                if (events || sysfs_events)
+                        continue;
+
                 if (kthread_should_stop())
                         break;
 
@@ -745,6 +775,30 @@ void pcmcia_parse_events(struct pcmcia_socket *s, u_int events)
 } /* pcmcia_parse_events */
 EXPORT_SYMBOL(pcmcia_parse_events);
 
+/**
+ * pcmcia_parse_uevents() - tell pccardd to issue manual commands
+ * @s:          the PCMCIA socket we wan't to command
+ * @events:     events to pass to pccardd
+ *
+ * userspace-issued insert, eject, suspend and resume commands must be
+ * handled by pccardd to avoid any sysfs-related deadlocks. Valid events
+ * are PCMCIA_UEVENT_EJECT (for eject), PCMCIA_UEVENT__INSERT (for insert),
+ * PCMCIA_UEVENT_RESUME (for resume) and PCMCIA_UEVENT_SUSPEND (for suspend).
+ */
+void pcmcia_parse_uevents(struct pcmcia_socket *s, u_int events)
+{
+        unsigned long flags;
+        dev_dbg(&s->dev, "parse_uevents: events %08x\n", events);
+        if (s->thread) {
+                spin_lock_irqsave(&s->thread_lock, flags);
+                s->sysfs_events |= events;
+                spin_unlock_irqrestore(&s->thread_lock, flags);
+
+                wake_up_process(s->thread);
+        }
+}
+EXPORT_SYMBOL(pcmcia_parse_uevents);
+
 
 /* register pcmcia_callback */
 int pccard_register_pcmcia(struct pcmcia_socket *s, struct pcmcia_callback *c)
@@ -828,121 +882,6 @@ int pcmcia_reset_card(struct pcmcia_socket *skt)
 EXPORT_SYMBOL(pcmcia_reset_card);
 
 
-/* These shut down or wake up a socket.  They are sort of user
- * initiated versions of the APM suspend and resume actions.
- */
-int pcmcia_suspend_card(struct pcmcia_socket *skt)
-{
-        int ret;
-
-        dev_dbg(&skt->dev, "suspending socket\n");
-
-        mutex_lock(&skt->skt_mutex);
-        do {
-                if (!(skt->state & SOCKET_PRESENT)) {
-                        ret = -ENODEV;
-                        break;
-                }
-                if (skt->state & SOCKET_CARDBUS) {
-                        ret = -EPERM;
-                        break;
-                }
-                if (skt->callback) {
-                        ret = skt->callback->suspend(skt);
-                        if (ret)
-                                break;
-                }
-                ret = socket_suspend(skt);
-        } while (0);
-        mutex_unlock(&skt->skt_mutex);
-
-        return ret;
-} /* suspend_card */
-EXPORT_SYMBOL(pcmcia_suspend_card);
-
-
-int pcmcia_resume_card(struct pcmcia_socket *skt)
-{
-        int ret;
-
-        dev_dbg(&skt->dev, "waking up socket\n");
-
-        mutex_lock(&skt->skt_mutex);
-        do {
-                if (!(skt->state & SOCKET_PRESENT)) {
-                        ret = -ENODEV;
-                        break;
-                }
-                if (skt->state & SOCKET_CARDBUS) {
-                        ret = -EPERM;
-                        break;
-                }
-                ret = socket_resume(skt);
-                if (!ret && skt->callback)
-                        skt->callback->resume(skt);
-        } while (0);
-        mutex_unlock(&skt->skt_mutex);
-
-        return ret;
-} /* resume_card */
-EXPORT_SYMBOL(pcmcia_resume_card);
-
-
-/* These handle user requests to eject or insert a card. */
-int pcmcia_eject_card(struct pcmcia_socket *skt)
-{
-        int ret;
-
-        dev_dbg(&skt->dev, "user eject request\n");
-
-        mutex_lock(&skt->skt_mutex);
-        do {
-                if (!(skt->state & SOCKET_PRESENT)) {
-                        ret = -ENODEV;
-                        break;
-                }
-
-                ret = send_event(skt, CS_EVENT_EJECTION_REQUEST, CS_EVENT_PRI_LOW);
-                if (ret != 0) {
-                        ret = -EINVAL;
-                        break;
-                }
-
-                socket_remove(skt);
-                ret = 0;
-        } while (0);
-        mutex_unlock(&skt->skt_mutex);
-
-        return ret;
-} /* eject_card */
-EXPORT_SYMBOL(pcmcia_eject_card);
-
-
-int pcmcia_insert_card(struct pcmcia_socket *skt)
-{
-        int ret;
-
-        dev_dbg(&skt->dev, "user insert request\n");
-
-        mutex_lock(&skt->skt_mutex);
-        do {
-                if (skt->state & SOCKET_PRESENT) {
-                        ret = -EBUSY;
-                        break;
-                }
-                if (socket_insert(skt) == -ENODEV) {
-                        ret = -ENODEV;
-                        break;
-                }
-                ret = 0;
-        } while (0);
-        mutex_unlock(&skt->skt_mutex);
-
-        return ret;
-} /* insert_card */
-EXPORT_SYMBOL(pcmcia_insert_card);
-
-
 static int pcmcia_socket_uevent(struct device *dev,
                                 struct kobj_uevent_env *env)
 {
diff --git a/drivers/pcmcia/cs_internal.h b/drivers/pcmcia/cs_internal.h
index bd386d77845e..127c97acf849 100644
--- a/drivers/pcmcia/cs_internal.h
+++ b/drivers/pcmcia/cs_internal.h
@@ -124,11 +124,11 @@ extern struct class pcmcia_socket_class;
 int pccard_register_pcmcia(struct pcmcia_socket *s, struct pcmcia_callback *c);
 struct pcmcia_socket *pcmcia_get_socket_by_nr(unsigned int nr);
 
-int pcmcia_suspend_card(struct pcmcia_socket *skt);
-int pcmcia_resume_card(struct pcmcia_socket *skt);
-
-int pcmcia_eject_card(struct pcmcia_socket *skt);
-int pcmcia_insert_card(struct pcmcia_socket *skt);
+void pcmcia_parse_uevents(struct pcmcia_socket *socket, unsigned int events);
+#define PCMCIA_UEVENT_EJECT     0x0001
+#define PCMCIA_UEVENT_INSERT    0x0002
+#define PCMCIA_UEVENT_SUSPEND   0x0004
+#define PCMCIA_UEVENT_RESUME    0x0008
 
 struct pcmcia_socket *pcmcia_get_socket(struct pcmcia_socket *skt);
 void pcmcia_put_socket(struct pcmcia_socket *skt);
diff --git a/drivers/pcmcia/pcmcia_ioctl.c b/drivers/pcmcia/pcmcia_ioctl.c
index 96fd236f52a9..13a7132cf688 100644
--- a/drivers/pcmcia/pcmcia_ioctl.c
+++ b/drivers/pcmcia/pcmcia_ioctl.c
@@ -925,16 +925,16 @@ static int ds_ioctl(struct inode *inode, struct file *file,
         ret = pccard_validate_cis(s, &buf->cisinfo.Chains);
         break;
     case DS_SUSPEND_CARD:
-        ret = pcmcia_suspend_card(s);
+        pcmcia_parse_uevents(s, PCMCIA_UEVENT_SUSPEND);
         break;
     case DS_RESUME_CARD:
-        ret = pcmcia_resume_card(s);
+        pcmcia_parse_uevents(s, PCMCIA_UEVENT_RESUME);
         break;
     case DS_EJECT_CARD:
-        err = pcmcia_eject_card(s);
+        pcmcia_parse_uevents(s, PCMCIA_UEVENT_EJECT);
         break;
     case DS_INSERT_CARD:
-        err = pcmcia_insert_card(s);
+        pcmcia_parse_uevents(s, PCMCIA_UEVENT_INSERT);
         break;
     case DS_ACCESS_CONFIGURATION_REGISTER:
         if ((buf->conf_reg.Action == CS_WRITE) && !capable(CAP_SYS_ADMIN)) {
diff --git a/drivers/pcmcia/socket_sysfs.c b/drivers/pcmcia/socket_sysfs.c
index e8826df00a36..fba0e30183f4 100644
--- a/drivers/pcmcia/socket_sysfs.c
+++ b/drivers/pcmcia/socket_sysfs.c
@@ -88,15 +88,14 @@ static DEVICE_ATTR(card_vcc, 0444, pccard_show_vcc, NULL);
 static ssize_t pccard_store_insert(struct device *dev, struct device_attribute *attr,
                                    const char *buf, size_t count)
 {
-        ssize_t ret;
         struct pcmcia_socket *s = to_socket(dev);
 
         if (!count)
                 return -EINVAL;
 
-        ret = pcmcia_insert_card(s);
+        pcmcia_parse_uevents(s, PCMCIA_UEVENT_INSERT);
 
-        return ret ? ret : count;
+        return count;
 }
 static DEVICE_ATTR(card_insert, 0200, NULL, pccard_store_insert);
 
@@ -113,18 +112,22 @@ static ssize_t pccard_store_card_pm_state(struct device *dev,
                                           struct device_attribute *attr,
                                           const char *buf, size_t count)
 {
-        ssize_t ret = -EINVAL;
         struct pcmcia_socket *s = to_socket(dev);
+        ssize_t ret = count;
 
         if (!count)
                 return -EINVAL;
 
-        if (!(s->state & SOCKET_SUSPEND) && !strncmp(buf, "off", 3))
-                ret = pcmcia_suspend_card(s);
-        else if ((s->state & SOCKET_SUSPEND) && !strncmp(buf, "on", 2))
-                ret = pcmcia_resume_card(s);
+        if (!strncmp(buf, "off", 3))
+                pcmcia_parse_uevents(s, PCMCIA_UEVENT_SUSPEND);
+        else {
+                if (!strncmp(buf, "on", 2))
+                        pcmcia_parse_uevents(s, PCMCIA_UEVENT_RESUME);
+                else
+                        ret = -EINVAL;
+        }
 
-        return ret ? -ENODEV : count;
+        return ret;
 }
 static DEVICE_ATTR(card_pm_state, 0644, pccard_show_card_pm_state, pccard_store_card_pm_state);
 
@@ -132,15 +135,14 @@ static ssize_t pccard_store_eject(struct device *dev,
                                   struct device_attribute *attr,
                                   const char *buf, size_t count)
 {
-        ssize_t ret;
         struct pcmcia_socket *s = to_socket(dev);
 
         if (!count)
                 return -EINVAL;
 
-        ret = pcmcia_eject_card(s);
+        pcmcia_parse_uevents(s, PCMCIA_UEVENT_EJECT);
 
-        return ret ? ret : count;
+        return count;
 }
 static DEVICE_ATTR(card_eject, 0200, NULL, pccard_store_eject);
 
diff --git a/include/pcmcia/ss.h b/include/pcmcia/ss.h
index cfaccc224b50..ea5dec8c0d76 100644
--- a/include/pcmcia/ss.h
+++ b/include/pcmcia/ss.h
@@ -200,13 +200,14 @@ struct pcmcia_socket {
         struct task_struct              *thread;
         struct completion               thread_done;
         unsigned int                    thread_events;
+        unsigned int                    sysfs_events;
 
         /* For the non-trivial interaction between these locks,
          * see Documentation/pcmcia/locking.txt */
         struct mutex                    skt_mutex;
         struct mutex                    ops_mutex;
 
-        /* protects thread_events */
+        /* protects thread_events and sysfs_events */
         spinlock_t                      thread_lock;
 
         /* pcmcia (16-bit) */