[PATCH] net/bnxt: fix unintialized warning

[PATCH] net/bnxt: fix unintialized warning

[Stephen Hemminger]

With gcc-16 it inlines a lot more code and creates a warnings
where it thinks it might be manipulating bits that are not set.
It looks like this is because the bits in control word (cword)
in theory could be larger than the variable. Should not
be possible because wc_ctl_size_bits is only set to 3, 16, or 32
but that happens outside of the scope of these functions.

Resolve by adding bounds check which compiler sees and knows
the loop will only see those bits.

In function ‘ulp_bs_push_msb’,
    inlined from ‘ulp_blob_push’ at ../drivers/net/bnxt/tf_ulp/ulp_utils.h:407:8,
    inlined from ‘ulp_blob_push_32’ at ../drivers/net/bnxt/tf_ulp/ulp_utils.h:551:7,
    inlined from ‘ulp_mapper_wc_tcam_tbl_dyn_post_process’ at ../drivers/net/bnxt/tf_ulp/ulp_mapper.c:2487:9:
../drivers/net/bnxt/tf_ulp/ulp_utils.h:336:17: warning: ‘cword’ may be used uninitialized [-Wmaybe-uninitialized]
  336 |                 ulp_bs_put_msb(bs, pos, 8, val[i]);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/net/bnxt/tf_ulp/ulp_mapper.c: In function ‘ulp_mapper_wc_tcam_tbl_dyn_post_process’:
../drivers/net/bnxt/tf_ulp/ulp_mapper.c:2443:18: note: ‘cword’ declared here
 2443 |         uint32_t cword, i, rc;
      |                  ^~~~~

Bugzilla ID: 1821
Fixes: 3fe124d2536c ("net/bnxt: support Thor platform")
Cc: stable@dpdk.org

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/net/bnxt/tf_ulp/ulp_mapper.c     | 5 +++++
 drivers/net/bnxt/tf_ulp/ulp_mapper_tfc.c | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/drivers/net/bnxt/tf_ulp/ulp_mapper.c b/drivers/net/bnxt/tf_ulp/ulp_mapper.c
index 0ff952950b..960cdda311 100644
--- a/drivers/net/bnxt/tf_ulp/ulp_mapper.c
+++ b/drivers/net/bnxt/tf_ulp/ulp_mapper.c
@@ -2446,6 +2446,11 @@ ulp_mapper_wc_tcam_tbl_dyn_post_process(struct bnxt_ulp_device_params *dparms,
 
 	slice_width = dparms->wc_slice_width;
 	clen = dparms->wc_ctl_size_bits;
+	if (clen > 32) {
+		BNXT_DRV_DBG(ERR, "Key size bits %d too large\n", clen);
+		return -EINVAL;
+	}
+
 	max_slices = dparms->wc_max_slices;
 	blen = ulp_blob_data_len_get(key);
 
diff --git a/drivers/net/bnxt/tf_ulp/ulp_mapper_tfc.c b/drivers/net/bnxt/tf_ulp/ulp_mapper_tfc.c
index f99698a1d8..2d89f10d5e 100644
--- a/drivers/net/bnxt/tf_ulp/ulp_mapper_tfc.c
+++ b/drivers/net/bnxt/tf_ulp/ulp_mapper_tfc.c
@@ -90,6 +90,10 @@ ulp_mapper_tfc_wc_tcam_post_process(struct bnxt_ulp_device_params *dparms,
 
 	slice_width = dparms->wc_slice_width;
 	clen = dparms->wc_ctl_size_bits;
+	if (clen > 32) {
+		BNXT_DRV_DBG(ERR, "Key size bits %d too large\n", clen);
+		return -EINVAL;
+	}
 	max_slices = dparms->wc_max_slices;
 	blen = ulp_blob_data_len_get(key);
 
-- 
2.51.0