greybus: loopback: warn user if kfifo cannot log all data

The depth of the kfifo used to log the latency data for user-space can be
moved upwards or downward by way of a module parameter. The user may still
specify a test set that's larger than the number of kfifo elements we have
available. If the user specifies more iterations than can be logged give a
warning as feedback and continue with the test.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/loopback.c b/drivers/staging/greybus/loopback.c
index 7b3ce13032c5ea43cfc282aa9816d1c1c8860585..08a77fee385ab0457a0c7851911e5faae5d8976f 100644 (file)
--- a/drivers/staging/greybus/loopback.c
+++ b/drivers/staging/greybus/loopback.c
@@ -131,14 +131,15 @@ static ssize_t field##_store(struct device *dev,                  \
        if (ret != 1)                                                   \
                len = -EINVAL;                                          \
        else                                                            \
-               gb_loopback_check_attr(gb);                             \
+               gb_loopback_check_attr(connection, gb);                 \
        mutex_unlock(&gb->mutex);                                       \
        return len;                                                     \
 }                                                                      \
 static DEVICE_ATTR_RW(field)
 
 static void gb_loopback_reset_stats(struct gb_loopback *gb);
-static void gb_loopback_check_attr(struct gb_loopback *gb)
+static void gb_loopback_check_attr(struct gb_connection *connection,
+                                  struct gb_loopback *gb)
 {
        if (gb->ms_wait > GB_LOOPBACK_MS_WAIT_MAX)
                gb->ms_wait = GB_LOOPBACK_MS_WAIT_MAX;
@@ -148,6 +149,12 @@ static void gb_loopback_check_attr(struct gb_loopback *gb)
        gb->iteration_count = 0;
        gb_loopback_reset_stats(gb);
 
+       if (kfifo_depth < gb->iteration_max) {
+               dev_warn(&connection->dev,
+                        "iteration_max %u kfifo_depth %u cannot log all data\n",
+                        gb->iteration_max, kfifo_depth);
+       }
+
        switch (gb->type) {
        case GB_LOOPBACK_TYPE_PING:
        case GB_LOOPBACK_TYPE_TRANSFER: