Re: [PATCH][next] drm/mm/selftests: fix unsigned comparison with less than zero

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




On 6/18/20 12:39 PM, Dan Carpenter wrote:
On Wed, Jun 17, 2020 at 04:59:59PM +0100, Colin King wrote:
From: Colin Ian King <colin.king@xxxxxxxxxxxxx>

Function get_insert_time can return error values that are cast
to a u64. The checks of insert_time1 and insert_time2 check for
the errors but because they are u64 variables the check for less
than zero can never be true. Fix this by casting the value to s64
to allow of the negative error check to succeed.

Addresses-Coverity: ("Unsigned compared against 0, no effect")
Fixes: 6e60d5ded06b ("drm/mm: add ig_frag selftest")
Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
---
  drivers/gpu/drm/selftests/test-drm_mm.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/selftests/test-drm_mm.c b/drivers/gpu/drm/selftests/test-drm_mm.c
index 3846b0f5bae3..671a152a6df2 100644
--- a/drivers/gpu/drm/selftests/test-drm_mm.c
+++ b/drivers/gpu/drm/selftests/test-drm_mm.c
@@ -1124,12 +1124,12 @@ static int igt_frag(void *ignored)
insert_time1 = get_insert_time(&mm, insert_size,
  					       nodes + insert_size, mode);
-		if (insert_time1 < 0)
+		if ((s64)insert_time1 < 0)
  			goto err;
The error codes in this function seem pretty messed up.

Speaking of error codes, what the heck is going on with
prepare_igt_frag().


This is on me. I will send a patch to correct this mistake.


Thanks,

Nirmoy



   1037  static int prepare_igt_frag(struct drm_mm *mm,
   1038                              struct drm_mm_node *nodes,
   1039                              unsigned int num_insert,
   1040                              const struct insert_mode *mode)
   1041  {
   1042          unsigned int size = 4096;
   1043          unsigned int i;
   1044          u64 ret = -EINVAL;
                 ^^^^^^^^^^^^^^^^^^
Why is it u64?

   1045
   1046          for (i = 0; i < num_insert; i++) {
   1047                  if (!expect_insert(mm, &nodes[i], size, 0, i,
   1048                                     mode) != 0) {
   1049                          pr_err("%s insert failed\n", mode->name);
   1050                          goto out;
                                 ^^^^^^^^
One of the common bugs with do nothing gotos is that we forget to set
the error code.  If we did a direct "return -EINVAL;" here, then there
would be no ambiguity.

   1051                  }
   1052          }
   1053
   1054          /* introduce fragmentation by freeing every other node */
   1055          for (i = 0; i < num_insert; i++) {
   1056                  if (i % 2 == 0)
   1057                          drm_mm_remove_node(&nodes[i]);
   1058          }
   1059
   1060  out:
   1061          return ret;
   1062
   1063  }

regards,
dan carpenter

_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.freedesktop.org%2Fmailman%2Flistinfo%2Fdri-devel&amp;data=02%7C01%7Cnirmoy.das%40amd.com%7C74bcb0163ea04eaf0ca008d8137403ac%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637280736306420244&amp;sdata=kZ7BUVaFWI5aV4OztJr8GMS8QWjz%2F7JIb9jwRM3ct5g%3D&amp;reserved=0



[Index of Archives]     [Kernel Development]     [Kernel Announce]     [Kernel Newbies]     [Linux Networking Development]     [Share Photos]     [IDE]     [Security]     [Git]     [Netfilter]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Device Mapper]

  Powered by Linux