misc: st_core: Protect unsigned value against becoming negative

Coverity reported:
  This less-than-zero comparison of an unsigned value is never true.

In answer to that, we only ever decrement if protos_registered is
positive.  We can subsequently remove the paranoid checking during
unregister.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/ti-st/st_core.c b/drivers/misc/ti-st/st_core.c
index 1972d57aadb30b9aa69304a9513f251864dd589e..54be83d3efdd682e8025577c5464f2c3807739c0 100644 (file)
--- a/drivers/misc/ti-st/st_core.c
+++ b/drivers/misc/ti-st/st_core.c
@@ -153,8 +153,9 @@ static void st_reg_complete(struct st_data_s *st_gdata, char err)
                                (st_gdata->list[i]->priv_data, err);
                        pr_info("protocol %d's cb sent %d\n", i, err);
                        if (err) { /* cleanup registered protocol */
-                               st_gdata->protos_registered--;
                                st_gdata->is_registered[i] = false;
+                               if (st_gdata->protos_registered)
+                                       st_gdata->protos_registered--;
                        }
                }
        }
@@ -639,14 +640,12 @@ long st_unregister(struct st_proto_s *proto)
                return -EPROTONOSUPPORT;
        }
 
-       st_gdata->protos_registered--;
+       if (st_gdata->protos_registered)
+               st_gdata->protos_registered--;
+
        remove_channel_from_table(st_gdata, proto);
        spin_unlock_irqrestore(&st_gdata->lock, flags);
 
-       /* paranoid check */
-       if (st_gdata->protos_registered < ST_EMPTY)
-               st_gdata->protos_registered = ST_EMPTY;
-
        if ((st_gdata->protos_registered == ST_EMPTY) &&
            (!test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
                pr_info(" all chnl_ids unregistered ");