vme: change bus error handling scheme

The current VME bus error handler adds errors to the bridge error list.
vme_master_{read,write} then traverses that list to look for relevant
errors.

Such scheme didn't work well for accesses going through vme_master_mmap
because they would also allocate a vme_bus_error, but have no way to do
vme_clear_errors call to free that memory.

This changes the error handling process to be other way around: now
vme_master_{read,write} defines a window in VME address space that will
catch possible errors.  VME bus error interrupt only traverses these
windows and marks those that had errors in them.

Signed-off-by: Dmitry Kalinkin <dmitry.kalinkin@gmail.com>
Cc: Igor Alekseev <igor.alekseev@itep.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 91 insertions, 110 deletions

diff --git a/drivers/vme/bridges/vme_ca91cx42.c b/drivers/vme/bridges/vme_ca91cx42.c
index 1d41cf21319b..b79a74a98a23 100644
--- a/drivers/vme/bridges/vme_ca91cx42.c
+++ b/drivers/vme/bridges/vme_ca91cx42.c
@@ -204,8 +204,7 @@ static int ca91cx42_irq_init(struct vme_bridge *ca91cx42_bridge)
         /* Need pdev */
         pdev = container_of(ca91cx42_bridge->parent, struct pci_dev, dev);
 
-        /* Initialise list for VME bus errors */
-        INIT_LIST_HEAD(&ca91cx42_bridge->vme_errors);
+        INIT_LIST_HEAD(&ca91cx42_bridge->vme_error_handlers);
 
         mutex_init(&ca91cx42_bridge->irq_mtx);
 
diff --git a/drivers/vme/bridges/vme_tsi148.c b/drivers/vme/bridges/vme_tsi148.c
index 4520d985379f..d1e383bc1f17 100644
--- a/drivers/vme/bridges/vme_tsi148.c
+++ b/drivers/vme/bridges/vme_tsi148.c
@@ -314,8 +314,7 @@ static int tsi148_irq_init(struct vme_bridge *tsi148_bridge)
 
         bridge = tsi148_bridge->driver_priv;
 
-        /* Initialise list for VME bus errors */
-        INIT_LIST_HEAD(&tsi148_bridge->vme_errors);
+        INIT_LIST_HEAD(&tsi148_bridge->vme_error_handlers);
 
         mutex_init(&tsi148_bridge->irq_mtx);
 
@@ -1187,7 +1186,7 @@ static ssize_t tsi148_master_read(struct vme_master_resource *image, void *buf,
         int retval, enabled;
         unsigned long long vme_base, size;
         u32 aspace, cycle, dwidth;
-        struct vme_bus_error *vme_err = NULL;
+        struct vme_error_handler *handler;
         struct vme_bridge *tsi148_bridge;
         void __iomem *addr = image->kern_base + offset;
         unsigned int done = 0;
@@ -1197,6 +1196,17 @@ static ssize_t tsi148_master_read(struct vme_master_resource *image, void *buf,
 
         spin_lock(&image->lock);
 
+        if (err_chk) {
+                __tsi148_master_get(image, &enabled, &vme_base, &size, &aspace,
+                                    &cycle, &dwidth);
+                handler = vme_register_error_handler(tsi148_bridge, aspace,
+                                                     vme_base + offset, count);
+                if (!handler) {
+                        spin_unlock(&image->lock);
+                        return -ENOMEM;
+                }
+        }
+
         /* The following code handles VME address alignment. We cannot use
          * memcpy_xxx here because it may cut data transfers in to 8-bit
          * cycles when D16 or D32 cycles are required on the VME bus.
@@ -1240,24 +1250,16 @@ static ssize_t tsi148_master_read(struct vme_master_resource *image, void *buf,
 out:
         retval = count;
 
-        if (!err_chk)
-                goto skip_chk;
-
-        __tsi148_master_get(image, &enabled, &vme_base, &size, &aspace, &cycle,
-                &dwidth);
-
-        vme_err = vme_find_error(tsi148_bridge, aspace, vme_base + offset,
-                count);
-        if (vme_err != NULL) {
-                dev_err(image->parent->parent, "First VME read error detected "
-                        "an at address 0x%llx\n", vme_err->address);
-                retval = vme_err->address - (vme_base + offset);
-                /* Clear down save errors in this address range */
-                vme_clear_errors(tsi148_bridge, aspace, vme_base + offset,
-                        count);
+        if (err_chk) {
+                if (handler->num_errors) {
+                        dev_err(image->parent->parent,
+                                "First VME read error detected an at address 0x%llx\n",
+                                handler->first_error);
+                        retval = handler->first_error - (vme_base + offset);
+                }
+                vme_unregister_error_handler(handler);
         }
 
-skip_chk:
         spin_unlock(&image->lock);
 
         return retval;
@@ -1274,7 +1276,7 @@ static ssize_t tsi148_master_write(struct vme_master_resource *image, void *buf,
         unsigned int done = 0;
         unsigned int count32;
 
-        struct vme_bus_error *vme_err = NULL;
+        struct vme_error_handler *handler;
         struct vme_bridge *tsi148_bridge;
         struct tsi148_driver *bridge;
 
@@ -1284,6 +1286,17 @@ static ssize_t tsi148_master_write(struct vme_master_resource *image, void *buf,
 
         spin_lock(&image->lock);
 
+        if (err_chk) {
+                __tsi148_master_get(image, &enabled, &vme_base, &size, &aspace,
+                                    &cycle, &dwidth);
+                handler = vme_register_error_handler(tsi148_bridge, aspace,
+                                                     vme_base + offset, count);
+                if (!handler) {
+                        spin_unlock(&image->lock);
+                        return -ENOMEM;
+                }
+        }
+
         /* Here we apply for the same strategy we do in master_read
          * function in order to assure the correct cycles.
          */
@@ -1333,30 +1346,18 @@ out:
          * We check for saved errors in the written address range/space.
          */
 
-        if (!err_chk)
-                goto skip_chk;
-
-        /*
-         * Get window info first, to maximise the time that the buffers may
-         * fluch on their own
-         */
-        __tsi148_master_get(image, &enabled, &vme_base, &size, &aspace, &cycle,
-                &dwidth);
-
-        ioread16(bridge->flush_image->kern_base + 0x7F000);
+        if (err_chk) {
+                ioread16(bridge->flush_image->kern_base + 0x7F000);
 
-        vme_err = vme_find_error(tsi148_bridge, aspace, vme_base + offset,
-                count);
-        if (vme_err != NULL) {
-                dev_warn(tsi148_bridge->parent, "First VME write error detected"
-                        " an at address 0x%llx\n", vme_err->address);
-                retval = vme_err->address - (vme_base + offset);
-                /* Clear down save errors in this address range */
-                vme_clear_errors(tsi148_bridge, aspace, vme_base + offset,
-                        count);
+                if (handler->num_errors) {
+                        dev_warn(tsi148_bridge->parent,
+                                 "First VME write error detected an at address 0x%llx\n",
+                                 handler->first_error);
+                        retval = handler->first_error - (vme_base + offset);
+                }
+                vme_unregister_error_handler(handler);
         }
 
-skip_chk:
         spin_unlock(&image->lock);
 
         return retval;
diff --git a/drivers/vme/vme.c b/drivers/vme/vme.c
index 2b79cd2715da..7a10d926ebb4 100644
--- a/drivers/vme/vme.c
+++ b/drivers/vme/vme.c
@@ -1026,76 +1026,52 @@ EXPORT_SYMBOL(vme_dma_free);
 void vme_bus_error_handler(struct vme_bridge *bridge,
                            unsigned long long address, int am)
 {
-        struct vme_bus_error *error;
-
-        error = kmalloc(sizeof(struct vme_bus_error), GFP_ATOMIC);
-        if (error) {
-                error->aspace = vme_get_aspace(am);
-                error->address = address;
-                list_add_tail(&error->list, &bridge->vme_errors);
-        } else {
-                dev_err(bridge->parent,
-                        "Unable to alloc memory for VMEbus Error reporting\n");
+        struct list_head *handler_pos = NULL;
+        struct vme_error_handler *handler;
+        u32 aspace = vme_get_aspace(am);
+
+        list_for_each(handler_pos, &bridge->vme_error_handlers) {
+                handler = list_entry(handler_pos, struct vme_error_handler,
+                                     list);
+                if ((aspace == handler->aspace) &&
+                    (address >= handler->start) &&
+                    (address < handler->end)) {
+                        if (!handler->num_errors)
+                                handler->first_error = address;
+                        if (handler->num_errors != UINT_MAX)
+                                handler->num_errors++;
+                }
         }
 }
 EXPORT_SYMBOL(vme_bus_error_handler);
 
-/*
- * Find the first error in this address range
- */
-struct vme_bus_error *vme_find_error(struct vme_bridge *bridge, u32 aspace,
-                                     unsigned long long address, size_t count)
+struct vme_error_handler *vme_register_error_handler(
+        struct vme_bridge *bridge, u32 aspace,
+        unsigned long long address, size_t len)
 {
-        struct list_head *err_pos;
-        struct vme_bus_error *vme_err, *valid = NULL;
-        unsigned long long bound;
-
-        bound = address + count;
+        struct vme_error_handler *handler;
 
-        err_pos = NULL;
-        /* Iterate through errors */
-        list_for_each(err_pos, &bridge->vme_errors) {
-                vme_err = list_entry(err_pos, struct vme_bus_error, list);
-                if ((vme_err->aspace == aspace) &&
-                    (vme_err->address >= address) &&
-                    (vme_err->address < bound)) {
+        handler = kmalloc(sizeof(*handler), GFP_KERNEL);
+        if (!handler)
+                return NULL;
 
-                        valid = vme_err;
-                        break;
-                }
-        }
+        handler->aspace = aspace;
+        handler->start = address;
+        handler->end = address + len;
+        handler->num_errors = 0;
+        handler->first_error = 0;
+        list_add_tail(&handler->list, &bridge->vme_error_handlers);
 
-        return valid;
+        return handler;
 }
-EXPORT_SYMBOL(vme_find_error);
+EXPORT_SYMBOL(vme_register_error_handler);
 
-/*
- * Clear errors in the provided address range.
- */
-void vme_clear_errors(struct vme_bridge *bridge, u32 aspace,
-                      unsigned long long address, size_t count)
+void vme_unregister_error_handler(struct vme_error_handler *handler)
 {
-        struct list_head *err_pos, *temp;
-        struct vme_bus_error *vme_err;
-        unsigned long long bound;
-
-        bound = address + count;
-
-        err_pos = NULL;
-        /* Iterate through errors */
-        list_for_each_safe(err_pos, temp, &bridge->vme_errors) {
-                vme_err = list_entry(err_pos, struct vme_bus_error, list);
-
-                if ((vme_err->aspace == aspace) &&
-                    (vme_err->address >= address) &&
-                    (vme_err->address < bound)) {
-
-                        list_del(err_pos);
-                        kfree(vme_err);
-                }
-        }
+        list_del(&handler->list);
+        kfree(handler);
 }
-EXPORT_SYMBOL(vme_clear_errors);
+EXPORT_SYMBOL(vme_unregister_error_handler);
 
 void vme_irq_handler(struct vme_bridge *bridge, int level, int statid)
 {
diff --git a/drivers/vme/vme_bridge.h b/drivers/vme/vme_bridge.h
index 92fbe18cbc42..397578a73883 100644
--- a/drivers/vme/vme_bridge.h
+++ b/drivers/vme/vme_bridge.h
@@ -75,10 +75,13 @@ struct vme_lm_resource {
         int monitors;
 };
 
-struct vme_bus_error {
+struct vme_error_handler {
         struct list_head list;
-        u32 aspace;
-        unsigned long long address;
+        unsigned long long start;       /* Beginning of error window */
+        unsigned long long end;         /* End of error window */
+        unsigned long long first_error; /* Address of the first error */
+        u32 aspace;                     /* Address space of error window*/
+        unsigned num_errors;            /* Number of errors */
 };
 
 struct vme_callback {
@@ -106,8 +109,10 @@ struct vme_bridge {
         struct list_head dma_resources;
         struct list_head lm_resources;
 
-        struct list_head vme_errors;    /* List for errors generated on VME */
-        struct list_head devices;       /* List of devices on this bridge */
+        /* List for registered errors handlers */
+        struct list_head vme_error_handlers;
+        /* List of devices on this bridge */
+        struct list_head devices;
 
         /* Bridge Info - XXX Move to private structure? */
         struct device *parent;  /* Parent device (eg. pdev->dev for PCI) */
@@ -168,13 +173,13 @@ struct vme_bridge {
 
 void vme_bus_error_handler(struct vme_bridge *bridge,
                            unsigned long long address, int am);
-struct vme_bus_error *vme_find_error(struct vme_bridge *bridge, u32 aspace,
-                                     unsigned long long address, size_t count);
-void vme_clear_errors(struct vme_bridge *bridge, u32 aspace,
-                      unsigned long long address, size_t count);
 void vme_irq_handler(struct vme_bridge *, int, int);
 
 int vme_register_bridge(struct vme_bridge *);
 void vme_unregister_bridge(struct vme_bridge *);
+struct vme_error_handler *vme_register_error_handler(
+        struct vme_bridge *bridge, u32 aspace,
+        unsigned long long address, size_t len);
+void vme_unregister_error_handler(struct vme_error_handler *handler);
 
 #endif /* _VME_BRIDGE_H_ */