[PATCH] iwlwifi: rs: fixup the return value type of iwl_legacy_rate_to_fw_idx()

[PATCH] iwlwifi: rs: fixup the return value type of iwl_legacy_rate_to_fw_idx()

[cgel.zte]

From: Ye Guojin <ye.guojin@zte.com.cn>

This was found by coccicheck:
./drivers/net/wireless/intel/iwlwifi/fw/rs.c, 147, 10-21, WARNING
Unsigned expression compared with zero legacy_rate < 0

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Ye Guojin <ye.guojin@zte.com.cn>
---
 drivers/net/wireless/intel/iwlwifi/fw/api/rs.h | 2 +-
 drivers/net/wireless/intel/iwlwifi/fw/rs.c     | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/fw/api/rs.h b/drivers/net/wireless/intel/iwlwifi/fw/api/rs.h
index a09081d7ed45..7794cd6d289d 100644
--- a/drivers/net/wireless/intel/iwlwifi/fw/api/rs.h
+++ b/drivers/net/wireless/intel/iwlwifi/fw/api/rs.h
@@ -710,7 +710,7 @@ struct iwl_lq_cmd {
 
 u8 iwl_fw_rate_idx_to_plcp(int idx);
 u32 iwl_new_rate_from_v1(u32 rate_v1);
-u32 iwl_legacy_rate_to_fw_idx(u32 rate_n_flags);
+int iwl_legacy_rate_to_fw_idx(u32 rate_n_flags);
 const struct iwl_rate_mcs_info *iwl_rate_mcs(int idx);
 const char *iwl_rs_pretty_ant(u8 ant);
 const char *iwl_rs_pretty_bw(int bw);
diff --git a/drivers/net/wireless/intel/iwlwifi/fw/rs.c b/drivers/net/wireless/intel/iwlwifi/fw/rs.c
index a21c3befd93b..3850881210e6 100644
--- a/drivers/net/wireless/intel/iwlwifi/fw/rs.c
+++ b/drivers/net/wireless/intel/iwlwifi/fw/rs.c
@@ -142,7 +142,7 @@ u32 iwl_new_rate_from_v1(u32 rate_v1)
 		}
 	/* if legacy format */
 	} else {
-		u32 legacy_rate = iwl_legacy_rate_to_fw_idx(rate_v1);
+		int legacy_rate = iwl_legacy_rate_to_fw_idx(rate_v1);
 
 		WARN_ON(legacy_rate < 0);
 		rate_v2 |= legacy_rate;
@@ -172,7 +172,7 @@ u32 iwl_new_rate_from_v1(u32 rate_v1)
 }
 IWL_EXPORT_SYMBOL(iwl_new_rate_from_v1);
 
-u32 iwl_legacy_rate_to_fw_idx(u32 rate_n_flags)
+int iwl_legacy_rate_to_fw_idx(u32 rate_n_flags)
 {
 	int rate = rate_n_flags & RATE_LEGACY_RATE_MSK_V1;
 	int idx;
-- 
2.25.1

Re: [PATCH] iwlwifi: rs: fixup the return value type of iwl_legacy_rate_to_fw_idx()

[Joe Perches]

On Wed, 2021-11-17 at 06:36 +0000, cgel.zte@gmail.com wrote:
> From: Ye Guojin <ye.guojin@zte.com.cn>
> 
> This was found by coccicheck:
> ./drivers/net/wireless/intel/iwlwifi/fw/rs.c, 147, 10-21, WARNING
> Unsigned expression compared with zero legacy_rate < 0
[]
> diff --git a/drivers/net/wireless/intel/iwlwifi/fw/rs.c b/drivers/net/wireless/intel/iwlwifi/fw/rs.c
[]
> @@ -142,7 +142,7 @@ u32 iwl_new_rate_from_v1(u32 rate_v1)
>  		}
>  	/* if legacy format */
>  	} else {
> -		u32 legacy_rate = iwl_legacy_rate_to_fw_idx(rate_v1);
> +		int legacy_rate = iwl_legacy_rate_to_fw_idx(rate_v1);
>  
>  		WARN_ON(legacy_rate < 0);

Why not just remove the WARN_ON instead?

Re: [PATCH] iwlwifi: rs: fixup the return value type of iwl_legacy_rate_to_fw_idx()

[Coelho, Luciano]

On Tue, 2021-11-16 at 22:41 -0800, Joe Perches wrote:
> On Wed, 2021-11-17 at 06:36 +0000, cgel.zte@gmail.com wrote:
> > From: Ye Guojin <ye.guojin@zte.com.cn>
> > 
> > This was found by coccicheck:
> > ./drivers/net/wireless/intel/iwlwifi/fw/rs.c, 147, 10-21, WARNING
> > Unsigned expression compared with zero legacy_rate < 0
> []
> > diff --git a/drivers/net/wireless/intel/iwlwifi/fw/rs.c b/drivers/net/wireless/intel/iwlwifi/fw/rs.c
> []
> > @@ -142,7 +142,7 @@ u32 iwl_new_rate_from_v1(u32 rate_v1)
> >  		}
> >  	/* if legacy format */
> >  	} else {
> > -		u32 legacy_rate = iwl_legacy_rate_to_fw_idx(rate_v1);
> > +		int legacy_rate = iwl_legacy_rate_to_fw_idx(rate_v1);
> >  
> >  		WARN_ON(legacy_rate < 0);
> 
> Why not just remove the WARN_ON instead?
> 

Well, iwl_legacy_rate_to_fw_idx() _tries_ to return -1 if we can't find
the index.

But there are a few more wrong things in this implementation:

1. the iwl_legacy_rate_to_fw_idx() function is only called inside the
fw/rs.c file, so it should be static;

2. if we don't find the idx and return -1, we WARN but still use the
value, which will cause the rate_v2 to be set to 0xffffffff, which I'm
pretty sure is not the intention.

So, this should be fixed properly, rather than just changing the
function to return int.

--
Cheers,
Luca.