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>

1 files changed, 48 insertions, 1 deletions

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index cdd205d6bf7c..c01f64780caf 100644
--- 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);           \