dma-debug: add variables and checks for driver filter

This patch adds the state variables for the driver filter and a function
to check if the filter is enabled and matches to the current device. The
check is built into the err_printk function.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index cdd205d..c01f647 100644 (file)
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -99,6 +99,15 @@ 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;
 
+/* 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" };
 
@@ -128,9 +137,47 @@ 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, 63) == 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);           \