diff options
| author |   Arnd Bergmann <arnd@arndb.de> | 2017-12-11 12:45:44 +0100 |
|---|---|---|
| committer |   Jason Gunthorpe <jgg@mellanox.com> | 2017-12-11 16:19:44 -0700 |
| commit | 1b19b95169cd52fe82cd442fec0b279fe25cc838 (patch) | |
| tree | 16dd21b20d789cbf7768aa80098d6db276a10bf8 /drivers | |
| parent | i40iw: Reinitialize add_sd_cnt (diff) | |
| download | linux-dev-1b19b95169cd52fe82cd442fec0b279fe25cc838.tar.xz linux-dev-1b19b95169cd52fe82cd442fec0b279fe25cc838.zip | |
IB/mlx5: revisit -Wmaybe-uninitialized warning
A warning that I thought I had fixed before occasionally comes
back in rare randconfig builds (I found 7 instances in the last
100000 builds, originally it was much more frequent):
drivers/infiniband/hw/mlx5/mr.c: In function 'mlx5_ib_reg_user_mr':
drivers/infiniband/hw/mlx5/mr.c:1229:5: error: 'order' may be used uninitialized in this function [-Werror=maybe-uninitialized]
if (order <= mr_cache_max_order(dev)) {
^
drivers/infiniband/hw/mlx5/mr.c:1247:8: error: 'ncont' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/infiniband/hw/mlx5/mr.c:1247:8: error: 'page_shift' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/infiniband/hw/mlx5/mr.c:1260:2: error: 'npages' may be used uninitialized in this function [-Werror=maybe-uninitialized]
I've looked at all those findings again and noticed that they are all
with CONFIG_INFINIBAND_USER_MEM=n, which means ib_umem_get() returns
an error unconditionally and we never initialize or use those variables.
This triggers a condition in gcc iff mr_umem_get() is partially but not
entirely inlined, which in turn depends on the exact combination of
optimization settings. This is a known problem with gcc, with no
easy solution in the compiler, so this adds another workaround that
should be more reliable than my previous attempt.
Returning an error from mlx5_ib_reg_user_mr() earlier means that we
can completely bypass the logic that caused the warning, the compiler
can now see that the variable is never accessed.
Fixes: 14ab8896f5d9 ("IB/mlx5: avoid bogus -Wmaybe-uninitialized warning")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/infiniband/hw/mlx5/mr.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c index ee0ee1f9994b..ad37d8441fa2 100644 --- a/drivers/infiniband/hw/mlx5/mr.c +++ b/drivers/infiniband/hw/mlx5/mr.c @@ -1206,6 +1206,9 @@ struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length, int err; bool use_umr = true; + if (!IS_ENABLED(CONFIG_INFINIBAND_USER_MEM)) + return ERR_PTR(-EINVAL); + mlx5_ib_dbg(dev, "start 0x%llx, virt_addr 0x%llx, length 0x%llx, access_flags 0x%x\n", start, virt_addr, length, access_flags); |