3 files changed, 288 insertions, 22 deletions

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index d9aa43d78bcc..25fb8bcf32a2 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -704,12 +704,24 @@ this directory the following files can currently be found:
                                 The current number of free dma_debug_entries
                                 in the allocator.
 
+        dma-api/driver-filter
+                                You can write a name of a driver into this file
+                                to limit the debug output to requests from that
+                                particular driver. Write an empty string to
+                                that file to disable the filter and see
+                                all errors again.
+
 If you have this code compiled into your kernel it will be enabled by default.
 If you want to boot without the bookkeeping anyway you can provide
 'dma_debug=off' as a boot parameter. This will disable DMA-API debugging.
 Notice that you can not enable it again at runtime. You have to reboot to do
 so.
 
+If you want to see debug messages only for a special device driver you can
+specify the dma_debug_driver=<drivername> parameter. This will enable the
+driver filter at boot time. The debug code will only print errors for that
+driver afterwards. This filter can be disabled or changed later using debugfs.
+
 When the code disables itself at runtime this is most likely because it ran
 out of dma_debug_entries. These entries are preallocated at boot. The number
 of preallocated entries is defined per architecture. If it is too low for you
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e2999cb4745a..8f9e17c855a0 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -641,6 +641,13 @@ and is between 256 and 4096 characters. It is defined in the file
                         DMA-API debugging code disables itself because the
                         architectural default is too low.
 
+        dma_debug_driver=<driver_name>
+                        With this option the DMA-API debugging driver
+                        filter feature can be enabled at boot time. Just
+                        pass the driver to filter for as the parameter.
+                        The filter can be disabled or changed to another
+                        driver later using sysfs.
+
         dscc4.setup=    [NET]
 
         dtc3181e=       [HW,SCSI]
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 8fcc09c91e1b..77053d9ef513 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -23,9 +23,11 @@
 #include <linux/dma-debug.h>
 #include <linux/spinlock.h>
 #include <linux/debugfs.h>
+#include <linux/uaccess.h>
 #include <linux/device.h>
 #include <linux/types.h>
 #include <linux/sched.h>
+#include <linux/ctype.h>
 #include <linux/list.h>
 #include <linux/slab.h>
 
@@ -98,6 +100,16 @@ static struct dentry *show_all_errors_dent  __read_mostly;
 static struct dentry *show_num_errors_dent  __read_mostly;
 static struct dentry *num_free_entries_dent __read_mostly;
 static struct dentry *min_free_entries_dent __read_mostly;
+static struct dentry *filter_dent           __read_mostly;
+
+/* per-driver filter related state */
+
+#define NAME_MAX_LEN    64
+
+static char                  current_driver_name[NAME_MAX_LEN] __read_mostly;
+static struct device_driver *current_driver                    __read_mostly;
+
+static DEFINE_RWLOCK(driver_name_lock);
 
 static const char *type2name[4] = { "single", "page",
                                     "scather-gather", "coherent" };
@@ -105,6 +117,11 @@ static const char *type2name[4] = { "single", "page",
 static const char *dir2name[4] = { "DMA_BIDIRECTIONAL", "DMA_TO_DEVICE",
                                    "DMA_FROM_DEVICE", "DMA_NONE" };
 
+/* little merge helper - remove it after the merge window */
+#ifndef BUS_NOTIFY_UNBOUND_DRIVER
+#define BUS_NOTIFY_UNBOUND_DRIVER 0x0005
+#endif
+
 /*
  * The access to some variables in this macro is racy. We can't use atomic_t
  * here because all these variables are exported to debugfs. Some of them even
@@ -128,9 +145,48 @@ static inline void dump_entry_trace(struct dma_debug_entry *entry)
 #endif
 }
 
+static bool driver_filter(struct device *dev)
+{
+        /* driver filter off */
+        if (likely(!current_driver_name[0]))
+                return true;
+
+        /* driver filter on and initialized */
+        if (current_driver && dev->driver == current_driver)
+                return true;
+
+        /* driver filter on but not yet initialized */
+        if (!current_driver && current_driver_name[0]) {
+                struct device_driver *drv = get_driver(dev->driver);
+                unsigned long flags;
+                bool ret = false;
+
+                if (!drv)
+                        return false;
+
+                /* lock to protect against change of current_driver_name */
+                read_lock_irqsave(&driver_name_lock, flags);
+
+                if (drv->name &&
+                    strncmp(current_driver_name, drv->name,
+                            NAME_MAX_LEN-1) == 0) {
+                        current_driver = drv;
+                        ret = true;
+                }
+
+                read_unlock_irqrestore(&driver_name_lock, flags);
+                put_driver(drv);
+
+                return ret;
+        }
+
+        return false;
+}
+
 #define err_printk(dev, entry, format, arg...) do {             \
                 error_count += 1;                               \
-                if (show_all_errors || show_num_errors > 0) {   \
+                if (driver_filter(dev) &&                       \
+                    (show_all_errors || show_num_errors > 0)) { \
                         WARN(1, "%s %s: " format,               \
                              dev_driver_string(dev),            \
                              dev_name(dev) , ## arg);           \
@@ -442,6 +498,97 @@ out_err:
         return -ENOMEM;
 }
 
+static ssize_t filter_read(struct file *file, char __user *user_buf,
+                           size_t count, loff_t *ppos)
+{
+        unsigned long flags;
+        char buf[NAME_MAX_LEN + 1];
+        int len;
+
+        if (!current_driver_name[0])
+                return 0;
+
+        /*
+         * We can't copy to userspace directly because current_driver_name can
+         * only be read under the driver_name_lock with irqs disabled. So
+         * create a temporary copy first.
+         */
+        read_lock_irqsave(&driver_name_lock, flags);
+        len = scnprintf(buf, NAME_MAX_LEN + 1, "%s\n", current_driver_name);
+        read_unlock_irqrestore(&driver_name_lock, flags);
+
+        return simple_read_from_buffer(user_buf, count, ppos, buf, len);
+}
+
+static ssize_t filter_write(struct file *file, const char __user *userbuf,
+                            size_t count, loff_t *ppos)
+{
+        unsigned long flags;
+        char buf[NAME_MAX_LEN];
+        size_t len = NAME_MAX_LEN - 1;
+        int i;
+
+        /*
+         * We can't copy from userspace directly. Access to
+         * current_driver_name is protected with a write_lock with irqs
+         * disabled. Since copy_from_user can fault and may sleep we
+         * need to copy to temporary buffer first
+         */
+        len = min(count, len);
+        if (copy_from_user(buf, userbuf, len))
+                return -EFAULT;
+
+        buf[len] = 0;
+
+        write_lock_irqsave(&driver_name_lock, flags);
+
+        /* Now handle the string we got from userspace very carefully.
+         * The rules are:
+         *         - only use the first token we got
+         *         - token delimiter is everything looking like a space
+         *           character (' ', '\n', '\t' ...)
+         *
+         */
+        if (!isalnum(buf[0])) {
+                /*
+                   If the first character userspace gave us is not
+                 * alphanumerical then assume the filter should be
+                 * switched off.
+                 */
+                if (current_driver_name[0])
+                        printk(KERN_INFO "DMA-API: switching off dma-debug "
+                                         "driver filter\n");
+                current_driver_name[0] = 0;
+                current_driver = NULL;
+                goto out_unlock;
+        }
+
+        /*
+         * Now parse out the first token and use it as the name for the
+         * driver to filter for.
+         */
+        for (i = 0; i < NAME_MAX_LEN; ++i) {
+                current_driver_name[i] = buf[i];
+                if (isspace(buf[i]) || buf[i] == ' ' || buf[i] == 0)
+                        break;
+        }
+        current_driver_name[i] = 0;
+        current_driver = NULL;
+
+        printk(KERN_INFO "DMA-API: enable driver filter for driver [%s]\n",
+               current_driver_name);
+
+out_unlock:
+        write_unlock_irqrestore(&driver_name_lock, flags);
+
+        return count;
+}
+
+const struct file_operations filter_fops = {
+        .read  = filter_read,
+        .write = filter_write,
+};
+
 static int dma_debug_fs_init(void)
 {
         dma_debug_dent = debugfs_create_dir("dma-api", NULL);
@@ -485,6 +632,11 @@ static int dma_debug_fs_init(void)
         if (!min_free_entries_dent)
                 goto out_err;
 
+        filter_dent = debugfs_create_file("driver_filter", 0644,
+                                          dma_debug_dent, NULL, &filter_fops);
+        if (!filter_dent)
+                goto out_err;
+
         return 0;
 
 out_err:
@@ -493,9 +645,60 @@ out_err:
         return -ENOMEM;
 }
 
+static int device_dma_allocations(struct device *dev)
+{
+        struct dma_debug_entry *entry;
+        unsigned long flags;
+        int count = 0, i;
+
+        for (i = 0; i < HASH_SIZE; ++i) {
+                spin_lock_irqsave(&dma_entry_hash[i].lock, flags);
+                list_for_each_entry(entry, &dma_entry_hash[i].list, list) {
+                        if (entry->dev == dev)
+                                count += 1;
+                }
+                spin_unlock_irqrestore(&dma_entry_hash[i].lock, flags);
+        }
+
+        return count;
+}
+
+static int dma_debug_device_change(struct notifier_block *nb,
+                                    unsigned long action, void *data)
+{
+        struct device *dev = data;
+        int count;
+
+
+        switch (action) {
+        case BUS_NOTIFY_UNBOUND_DRIVER:
+                count = device_dma_allocations(dev);
+                if (count == 0)
+                        break;
+                err_printk(dev, NULL, "DMA-API: device driver has pending "
+                                "DMA allocations while released from device "
+                                "[count=%d]\n", count);
+                break;
+        default:
+                break;
+        }
+
+        return 0;
+}
+
 void dma_debug_add_bus(struct bus_type *bus)
 {
-        /* FIXME: register notifier */
+        struct notifier_block *nb;
+
+        nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
+        if (nb == NULL) {
+                printk(KERN_ERR "dma_debug_add_bus: out of memory\n");
+                return;
+        }
+
+        nb->notifier_call = dma_debug_device_change;
+
+        bus_register_notifier(bus, nb);
 }
 
 /*
@@ -818,15 +1021,15 @@ void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
                 entry->type           = dma_debug_sg;
                 entry->dev            = dev;
                 entry->paddr          = sg_phys(s);
-                entry->size           = s->length;
-                entry->dev_addr       = s->dma_address;
+                entry->size           = sg_dma_len(s);
+                entry->dev_addr       = sg_dma_address(s);
                 entry->direction      = direction;
                 entry->sg_call_ents   = nents;
                 entry->sg_mapped_ents = mapped_ents;
 
                 if (!PageHighMem(sg_page(s))) {
                         check_for_stack(dev, sg_virt(s));
-                        check_for_illegal_area(dev, sg_virt(s), s->length);
+                        check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
                 }
 
                 add_dma_entry(entry);
@@ -834,13 +1037,32 @@ void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
 }
 EXPORT_SYMBOL(debug_dma_map_sg);
 
+static int get_nr_mapped_entries(struct device *dev, struct scatterlist *s)
+{
+        struct dma_debug_entry *entry;
+        struct hash_bucket *bucket;
+        unsigned long flags;
+        int mapped_ents = 0;
+        struct dma_debug_entry ref;
+
+        ref.dev = dev;
+        ref.dev_addr = sg_dma_address(s);
+        ref.size = sg_dma_len(s),
+
+        bucket = get_hash_bucket(&ref, &flags);
+        entry = hash_bucket_find(bucket, &ref);
+        if (entry)
+                mapped_ents = entry->sg_mapped_ents;
+        put_hash_bucket(bucket, &flags);
+
+        return mapped_ents;
+}
+
 void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
                         int nelems, int dir)
 {
-        struct dma_debug_entry *entry;
         struct scatterlist *s;
         int mapped_ents = 0, i;
-        unsigned long flags;
 
         if (unlikely(global_disable))
                 return;
@@ -851,8 +1073,8 @@ void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
                         .type           = dma_debug_sg,
                         .dev            = dev,
                         .paddr          = sg_phys(s),
-                        .dev_addr       = s->dma_address,
-                        .size           = s->length,
+                        .dev_addr       = sg_dma_address(s),
+                        .size           = sg_dma_len(s),
                         .direction      = dir,
                         .sg_call_ents   = 0,
                 };
@@ -860,14 +1082,9 @@ void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
                 if (mapped_ents && i >= mapped_ents)
                         break;
 
-                if (mapped_ents == 0) {
-                        struct hash_bucket *bucket;
+                if (!i) {
                         ref.sg_call_ents = nelems;
-                        bucket = get_hash_bucket(&ref, &flags);
-                        entry = hash_bucket_find(bucket, &ref);
-                        if (entry)
-                                mapped_ents = entry->sg_mapped_ents;
-                        put_hash_bucket(bucket, &flags);
+                        mapped_ents = get_nr_mapped_entries(dev, s);
                 }
 
                 check_unmap(&ref);
@@ -969,14 +1186,20 @@ void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
                                int nelems, int direction)
 {
         struct scatterlist *s;
-        int i;
+        int mapped_ents = 0, i;
 
         if (unlikely(global_disable))
                 return;
 
         for_each_sg(sg, s, nelems, i) {
-                check_sync(dev, s->dma_address, s->dma_length, 0,
-                                direction, true);
+                if (!i)
+                        mapped_ents = get_nr_mapped_entries(dev, s);
+
+                if (i >= mapped_ents)
+                        break;
+
+                check_sync(dev, sg_dma_address(s), sg_dma_len(s), 0,
+                           direction, true);
         }
 }
 EXPORT_SYMBOL(debug_dma_sync_sg_for_cpu);
@@ -985,15 +1208,39 @@ void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
                                   int nelems, int direction)
 {
         struct scatterlist *s;
-        int i;
+        int mapped_ents = 0, i;
 
         if (unlikely(global_disable))
                 return;
 
         for_each_sg(sg, s, nelems, i) {
-                check_sync(dev, s->dma_address, s->dma_length, 0,
-                                direction, false);
+                if (!i)
+                        mapped_ents = get_nr_mapped_entries(dev, s);
+
+                if (i >= mapped_ents)
+                        break;
+
+                check_sync(dev, sg_dma_address(s), sg_dma_len(s), 0,
+                           direction, false);
         }
 }
 EXPORT_SYMBOL(debug_dma_sync_sg_for_device);
 
+static int __init dma_debug_driver_setup(char *str)
+{
+        int i;
+
+        for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) {
+                current_driver_name[i] = *str;
+                if (*str == 0)
+                        break;
+        }
+
+        if (current_driver_name[0])
+                printk(KERN_INFO "DMA-API: enable driver filter for "
+                                 "driver [%s]\n", current_driver_name);
+
+
+        return 1;
+}
+__setup("dma_debug_driver=", dma_debug_driver_setup);