dmaengine: dmatest: Prevent to run on misconfigured channel

Andy reported that commit 6b41030fdc79 ("dmaengine: dmatest:
Restore default for channel") broke his scripts for the case
where "busy" channel is used for configuration with expectation
that run command would do nothing. Instead, behavior was
(unintentionally) changed to treat such case as under-configuration
and progress with defaults, i.e. run command would start a test
with default setting for channel (which would use all channels).

Restore original behavior with tracking status of channel setter
so we can distinguish between misconfigured and under-configured
cases in run command and act accordingly.

Fixes: 6b41030fdc79 ("dmaengine: dmatest: Restore default for channel")
Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200922115847.30100-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index 45d4d92e91dbf39f1e3380b2368f71d28d7961cc..a819611b8892c23f45ea414a004dc2b9f66e00e7 100644 (file)
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -129,6 +129,7 @@ struct dmatest_params {
  * @nr_channels:       number of channels under test
  * @lock:              access protection to the fields of this structure
  * @did_init:          module has been initialized completely
+ * @last_error:                test has faced configuration issues
  */
 static struct dmatest_info {
        /* Test parameters */
@@ -137,6 +138,7 @@ static struct dmatest_info {
        /* Internal state */
        struct list_head        channels;
        unsigned int            nr_channels;
+       int                     last_error;
        struct mutex            lock;
        bool                    did_init;
 } test_info = {
@@ -1184,10 +1186,22 @@ static int dmatest_run_set(const char *val, const struct kernel_param *kp)
                return ret;
        } else if (dmatest_run) {
                if (!is_threaded_test_pending(info)) {
-                       pr_info("No channels configured, continue with any\n");
-                       if (!is_threaded_test_run(info))
-                               stop_threaded_test(info);
-                       add_threaded_test(info);
+                       /*
+                        * We have nothing to run. This can be due to:
+                        */
+                       ret = info->last_error;
+                       if (ret) {
+                               /* 1) Misconfiguration */
+                               pr_err("Channel misconfigured, can't continue\n");
+                               mutex_unlock(&info->lock);
+                               return ret;
+                       } else {
+                               /* 2) We rely on defaults */
+                               pr_info("No channels configured, continue with any\n");
+                               if (!is_threaded_test_run(info))
+                                       stop_threaded_test(info);
+                               add_threaded_test(info);
+                       }
                }
                start_threaded_tests(info);
        } else {
@@ -1204,7 +1218,7 @@ static int dmatest_chan_set(const char *val, const struct kernel_param *kp)
        struct dmatest_info *info = &test_info;
        struct dmatest_chan *dtc;
        char chan_reset_val[20];
-       int ret = 0;
+       int ret;
 
        mutex_lock(&info->lock);
        ret = param_set_copystring(val, kp);
@@ -1259,12 +1273,14 @@ static int dmatest_chan_set(const char *val, const struct kernel_param *kp)
                goto add_chan_err;
        }
 
+       info->last_error = ret;
        mutex_unlock(&info->lock);
 
        return ret;
 
 add_chan_err:
        param_set_copystring(chan_reset_val, kp);
+       info->last_error = ret;
        mutex_unlock(&info->lock);
 
        return ret;