linux-kernel - [PATCH v2] iwlwifi: mvm: Use div_s64 instead of do_div in iwl_mvm_debug_range

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Message-Id: <20190221080617.2795-1-natechancellor@gmail.com>
Date:   Thu, 21 Feb 2019 01:06:18 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Johannes Berg <johannes.berg@...el.com>,
        Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
        Luca Coelho <luciano.coelho@...el.com>,
        Intel Linux Wireless <linuxwifi@...el.com>,
        Kalle Valo <kvalo@...eaurora.org>
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>
Subject: [PATCH v2] iwlwifi: mvm: Use div_s64 instead of do_div in iwl_mvm_debug_range_resp

Clang warns:

drivers/net/wireless/intel/iwlwifi/mvm/ftm-initiator.c:465:2: warning:
comparison of distinct pointer types ('typeof ((rtt_avg)) *' (aka 'long
long *') and 'uint64_t *' (aka 'unsigned long long *'))
[-Wcompare-distinct-pointer-types]
        do_div(rtt_avg, 6666);
        ^~~~~~~~~~~~~~~~~~~~~
include/asm-generic/div64.h:222:28: note: expanded from macro 'do_div'
        (void)(((typeof((n)) *)0) == ((uint64_t *)0));  \
               ~~~~~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~~~
1 warning generated.

do_div expects an unsigned dividend. Use div_s64, which expects a signed
dividend.

Fixes: 937b10c0de68 ("iwlwifi: mvm: add debug prints for FTM")
Link: https://github.com/ClangBuiltLinux/linux/issues/372
Suggested-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
---

v1 -> v2:

* Fix logic (as the return value of div{,64}_s64 must be used), thanks
  to Arnd for the review.

 drivers/net/wireless/intel/iwlwifi/mvm/ftm-initiator.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/ftm-initiator.c b/drivers/net/wireless/intel/iwlwifi/mvm/ftm-initiator.c
index e9822a3ec373..94132cfd1f56 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/ftm-initiator.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/ftm-initiator.c
@@ -460,9 +460,7 @@ static int iwl_mvm_ftm_range_resp_valid(struct iwl_mvm *mvm, u8 request_id,
 static void iwl_mvm_debug_range_resp(struct iwl_mvm *mvm, u8 index,
 				     struct cfg80211_pmsr_result *res)
 {
-	s64 rtt_avg = res->ftm.rtt_avg * 100;
-
-	do_div(rtt_avg, 6666);
+	s64 rtt_avg = div_s64(res->ftm.rtt_avg * 100, 6666);
 
 	IWL_DEBUG_INFO(mvm, "entry %d\n", index);
 	IWL_DEBUG_INFO(mvm, "\tstatus: %d\n", res->status);
-- 
2.21.0.rc1