drivers/edac: fix edac_pci sysfs

This patch fixes sysfs exit code for the EDAC PCI device in a similiar manner
and the previous fixes for EDAC_MC and EDAC_DEVICE.

It removes the old (and incorrect) completion model and uses reference counts
on per instance kobjects and on the edac core module.

This pattern was applied to the edac_mc and edac_device code, but the EDAC PCI
code was missed.  In addition, this fixes a system hang after a low level
driver was unloaded.  (A cleanup function was called twice, which really
screwed things up)

Cc: Greg KH <greg@kroah.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by:  Doug Thompson <dougthompson@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 111 insertions, 51 deletions

diff --git a/drivers/edac/edac_pci.c b/drivers/edac/edac_pci.c
index d9cd5e048cee..5dee9f50414b 100644
--- a/drivers/edac/edac_pci.c
+++ b/drivers/edac/edac_pci.c
@@ -31,20 +31,12 @@
 static DEFINE_MUTEX(edac_pci_ctls_mutex);
 static struct list_head edac_pci_list = LIST_HEAD_INIT(edac_pci_list);
 
-static inline void edac_lock_pci_list(void)
-{
-        mutex_lock(&edac_pci_ctls_mutex);
-}
-
-static inline void edac_unlock_pci_list(void)
-{
-        mutex_unlock(&edac_pci_ctls_mutex);
-}
-
 /*
- * The alloc() and free() functions for the 'edac_pci' control info
- * structure. The chip driver will allocate one of these for each
- * edac_pci it is going to control/register with the EDAC CORE.
+ * edac_pci_alloc_ctl_info
+ *
+ *      The alloc() function for the 'edac_pci' control info
+ *      structure. The chip driver will allocate one of these for each
+ *      edac_pci it is going to control/register with the EDAC CORE.
  */
 struct edac_pci_ctl_info *edac_pci_alloc_ctl_info(unsigned int sz_pvt,
                                                 const char *edac_pci_name)
@@ -53,47 +45,59 @@ struct edac_pci_ctl_info *edac_pci_alloc_ctl_info(unsigned int sz_pvt,
         void *pvt;
         unsigned int size;
 
+        debugf1("%s()\n", __func__);
+
         pci = (struct edac_pci_ctl_info *)0;
         pvt = edac_align_ptr(&pci[1], sz_pvt);
         size = ((unsigned long)pvt) + sz_pvt;
 
-        if ((pci = kzalloc(size, GFP_KERNEL)) == NULL)
+        /* Alloc the needed control struct memory */
+        pci = kzalloc(size, GFP_KERNEL);
+        if (pci  == NULL)
                 return NULL;
 
+        /* Now much private space */
         pvt = sz_pvt ? ((char *)pci) + ((unsigned long)pvt) : NULL;
 
         pci->pvt_info = pvt;
-
         pci->op_state = OP_ALLOC;
 
         snprintf(pci->name, strlen(edac_pci_name) + 1, "%s", edac_pci_name);
 
         return pci;
 }
-
 EXPORT_SYMBOL_GPL(edac_pci_alloc_ctl_info);
 
 /*
  * edac_pci_free_ctl_info()
- *      frees the memory allocated by edac_pci_alloc_ctl_info() function
+ *
+ *      Last action on the pci control structure.
+ *
+ *      call the remove sysfs informaton, which will unregister
+ *      this control struct's kobj. When that kobj's ref count
+ *      goes to zero, its release function will be call and then
+ *      kfree() the memory.
  */
 void edac_pci_free_ctl_info(struct edac_pci_ctl_info *pci)
 {
-        kfree(pci);
-}
+        debugf1("%s()\n", __func__);
 
+        edac_pci_remove_sysfs(pci);
+}
 EXPORT_SYMBOL_GPL(edac_pci_free_ctl_info);
 
 /*
  * find_edac_pci_by_dev()
  *      scans the edac_pci list for a specific 'struct device *'
+ *
+ *      return NULL if not found, or return control struct pointer
  */
 static struct edac_pci_ctl_info *find_edac_pci_by_dev(struct device *dev)
 {
         struct edac_pci_ctl_info *pci;
         struct list_head *item;
 
-        debugf3("%s()\n", __func__);
+        debugf1("%s()\n", __func__);
 
         list_for_each(item, &edac_pci_list) {
                 pci = list_entry(item, struct edac_pci_ctl_info, link);
@@ -118,10 +122,13 @@ static int add_edac_pci_to_global_list(struct edac_pci_ctl_info *pci)
         struct list_head *item, *insert_before;
         struct edac_pci_ctl_info *rover;
 
+        debugf1("%s()\n", __func__);
+
         insert_before = &edac_pci_list;
 
         /* Determine if already on the list */
-        if (unlikely((rover = find_edac_pci_by_dev(pci->dev)) != NULL))
+        rover = find_edac_pci_by_dev(pci->dev);
+        if (unlikely(rover != NULL))
                 goto fail0;
 
         /* Insert in ascending order by 'pci_idx', so find position */
@@ -157,6 +164,8 @@ fail1:
 
 /*
  * complete_edac_pci_list_del
+ *
+ *      RCU completion callback to indicate item is deleted
  */
 static void complete_edac_pci_list_del(struct rcu_head *head)
 {
@@ -169,6 +178,8 @@ static void complete_edac_pci_list_del(struct rcu_head *head)
 
 /*
  * del_edac_pci_from_global_list
+ *
+ *      remove the PCI control struct from the global list
  */
 static void del_edac_pci_from_global_list(struct edac_pci_ctl_info *pci)
 {
@@ -207,35 +218,52 @@ struct edac_pci_ctl_info *edac_pci_find(int idx)
 
         return NULL;
 }
-
 EXPORT_SYMBOL_GPL(edac_pci_find);
 
 /*
  * edac_pci_workq_function()
- *      performs the operation scheduled by a workq request
+ *
+ *      periodic function that performs the operation
+ *      scheduled by a workq request, for a given PCI control struct
  */
 static void edac_pci_workq_function(struct work_struct *work_req)
 {
         struct delayed_work *d_work = (struct delayed_work *)work_req;
         struct edac_pci_ctl_info *pci = to_edac_pci_ctl_work(d_work);
+        int msec;
+        unsigned long delay;
 
-        edac_lock_pci_list();
+        debugf3("%s() checking\n", __func__);
 
-        if ((pci->op_state == OP_RUNNING_POLL) &&
-                (pci->edac_check != NULL) && (edac_pci_get_check_errors()))
-                pci->edac_check(pci);
+        mutex_lock(&edac_pci_ctls_mutex);
 
-        edac_unlock_pci_list();
+        if (pci->op_state == OP_RUNNING_POLL) {
+                /* we might be in POLL mode, but there may NOT be a poll func
+                 */
+                if ((pci->edac_check != NULL) && edac_pci_get_check_errors())
+                        pci->edac_check(pci);
+
+                /* if we are on a one second period, then use round */
+                msec = edac_pci_get_poll_msec();
+                if (msec == 1000)
+                        delay = round_jiffies(msecs_to_jiffies(msec));
+                else
+                        delay = msecs_to_jiffies(msec);
+
+                /* Reschedule only if we are in POLL mode */
+                queue_delayed_work(edac_workqueue, &pci->work, delay);
+        }
 
-        /* Reschedule */
-        queue_delayed_work(edac_workqueue, &pci->work,
-                        msecs_to_jiffies(edac_pci_get_poll_msec()));
+        mutex_unlock(&edac_pci_ctls_mutex);
 }
 
 /*
  * edac_pci_workq_setup()
  *      initialize a workq item for this edac_pci instance
  *      passing in the new delay period in msec
+ *
+ *      locking model:
+ *              called when 'edac_pci_ctls_mutex' is locked
  */
 static void edac_pci_workq_setup(struct edac_pci_ctl_info *pci,
                                  unsigned int msec)
@@ -255,6 +283,8 @@ static void edac_pci_workq_teardown(struct edac_pci_ctl_info *pci)
 {
         int status;
 
+        debugf0("%s()\n", __func__);
+
         status = cancel_delayed_work(&pci->work);
         if (status == 0)
                 flush_workqueue(edac_workqueue);
@@ -262,19 +292,25 @@ static void edac_pci_workq_teardown(struct edac_pci_ctl_info *pci)
 
 /*
  * edac_pci_reset_delay_period
+ *
+ *      called with a new period value for the workq period
+ *      a) stop current workq timer
+ *      b) restart workq timer with new value
  */
 void edac_pci_reset_delay_period(struct edac_pci_ctl_info *pci,
                                  unsigned long value)
 {
-        edac_lock_pci_list();
+        debugf0("%s()\n", __func__);
 
         edac_pci_workq_teardown(pci);
 
+        /* need to lock for the setup */
+        mutex_lock(&edac_pci_ctls_mutex);
+
         edac_pci_workq_setup(pci, value);
 
-        edac_unlock_pci_list();
+        mutex_unlock(&edac_pci_ctls_mutex);
 }
-
 EXPORT_SYMBOL_GPL(edac_pci_reset_delay_period);
 
 /*
@@ -294,14 +330,13 @@ int edac_pci_add_device(struct edac_pci_ctl_info *pci, int edac_idx)
         debugf0("%s()\n", __func__);
 
         pci->pci_idx = edac_idx;
+        pci->start_time = jiffies;
 
-        edac_lock_pci_list();
+        mutex_lock(&edac_pci_ctls_mutex);
 
         if (add_edac_pci_to_global_list(pci))
                 goto fail0;
 
-        pci->start_time = jiffies;
-
         if (edac_pci_create_sysfs(pci)) {
                 edac_pci_printk(pci, KERN_WARNING,
                                 "failed to create sysfs pci\n");
@@ -323,16 +358,16 @@ int edac_pci_add_device(struct edac_pci_ctl_info *pci, int edac_idx)
                         pci->ctl_name,
                         dev_name(pci), edac_op_state_to_string(pci->op_state));
 
-        edac_unlock_pci_list();
+        mutex_unlock(&edac_pci_ctls_mutex);
         return 0;
 
+        /* error unwind stack */
 fail1:
         del_edac_pci_from_global_list(pci);
 fail0:
-        edac_unlock_pci_list();
+        mutex_unlock(&edac_pci_ctls_mutex);
         return 1;
 }
-
 EXPORT_SYMBOL_GPL(edac_pci_add_device);
 
 /*
@@ -354,22 +389,25 @@ struct edac_pci_ctl_info *edac_pci_del_device(struct device *dev)
 
         debugf0("%s()\n", __func__);
 
-        edac_lock_pci_list();
+        mutex_lock(&edac_pci_ctls_mutex);
 
-        if ((pci = find_edac_pci_by_dev(dev)) == NULL) {
-                edac_unlock_pci_list();
+        /* ensure the control struct is on the global list
+         * if not, then leave
+         */
+        pci = find_edac_pci_by_dev(dev);
+        if (pci  == NULL) {
+                mutex_unlock(&edac_pci_ctls_mutex);
                 return NULL;
         }
 
         pci->op_state = OP_OFFLINE;
 
-        edac_pci_workq_teardown(pci);
-
-        edac_pci_remove_sysfs(pci);
-
         del_edac_pci_from_global_list(pci);
 
-        edac_unlock_pci_list();
+        mutex_unlock(&edac_pci_ctls_mutex);
+
+        /* stop the workq timer */
+        edac_pci_workq_teardown(pci);
 
         edac_printk(KERN_INFO, EDAC_PCI,
                 "Removed device %d for %s %s: DEV %s\n",
@@ -377,14 +415,20 @@ struct edac_pci_ctl_info *edac_pci_del_device(struct device *dev)
 
         return pci;
 }
-
 EXPORT_SYMBOL_GPL(edac_pci_del_device);
 
+/*
+ * edac_pci_generic_check
+ *
+ *      a Generic parity check API
+ */
 void edac_pci_generic_check(struct edac_pci_ctl_info *pci)
 {
+        debugf4("%s()\n", __func__);
         edac_pci_do_parity_check();
 }
 
+/* free running instance index counter */
 static int edac_pci_idx;
 #define EDAC_PCI_GENCTL_NAME    "EDAC PCI controller"
 
@@ -392,6 +436,17 @@ struct edac_pci_gen_data {
         int edac_idx;
 };
 
+/*
+ * edac_pci_create_generic_ctl
+ *
+ *      A generic constructor for a PCI parity polling device
+ *      Some systems have more than one domain of PCI busses.
+ *      For systems with one domain, then this API will
+ *      provide for a generic poller.
+ *
+ *      This routine calls the edac_pci_alloc_ctl_info() for
+ *      the generic device, with default values
+ */
 struct edac_pci_ctl_info *edac_pci_create_generic_ctl(struct device *dev,
                                                 const char *mod_name)
 {
@@ -421,13 +476,18 @@ struct edac_pci_ctl_info *edac_pci_create_generic_ctl(struct device *dev,
 
         return pci;
 }
-
 EXPORT_SYMBOL_GPL(edac_pci_create_generic_ctl);
 
+/*
+ * edac_pci_release_generic_ctl
+ *
+ *      The release function of a generic EDAC PCI polling device
+ */
 void edac_pci_release_generic_ctl(struct edac_pci_ctl_info *pci)
 {
+        debugf0("%s() pci mod=%s\n", __func__, pci->mod_name);
+
         edac_pci_del_device(pci->dev);
         edac_pci_free_ctl_info(pci);
 }
-
 EXPORT_SYMBOL_GPL(edac_pci_release_generic_ctl);