linux-kernel - [PATCH net-next] net: ipa: always inline ipa_aggr_granularity

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Date:   Tue, 10 Aug 2021 11:02:13 -0500
From:   Alex Elder <elder@...aro.org>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     bjorn.andersson@...aro.org, evgreen@...omium.org,
        cpratapa@...eaurora.org, subashab@...eaurora.org, lkp@...el.com,
        elder@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next] net: ipa: always inline ipa_aggr_granularity_val()

It isn't required, but all callers of ipa_aggr_granularity_val()
pass a constant value (IPA_AGGR_GRANULARITY) as the usec argument.
Two of those callers are in ipa_validate_build(), with the result
being passed to BUILD_BUG_ON().

Evidently the "sparc64-linux-gcc" compiler (at least) doesn't always
inline ipa_aggr_granularity_val(), so the result of the function is
not constant at compile time, and that leads to build errors.

Define the function with the __always_inline attribute to avoid the
errors.  And given that the function is inline, we can switch the
WARN_ON() there to be BUILD_BUG_ON().

Fixes: 5bc5588466a1f ("net: ipa: use WARN_ON() rather than assertions")
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Alex Elder <elder@...aro.org>
---

David/Jakub, this fixes a bug in a commit in net-next/master.  -Alex

 drivers/net/ipa/ipa_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
index 25bbb456e0078..f90b3521e266b 100644
--- a/drivers/net/ipa/ipa_main.c
+++ b/drivers/net/ipa/ipa_main.c
@@ -255,9 +255,9 @@ ipa_hardware_config_qsb(struct ipa *ipa, const struct ipa_data *data)
  * less than the number of timer ticks in the requested period.  0 is not
  * a valid granularity value.
  */
-static u32 ipa_aggr_granularity_val(u32 usec)
+static __always_inline u32 ipa_aggr_granularity_val(u32 usec)
 {
-	WARN_ON(!usec);
+	BUILD_BUG_ON(!usec);

 	return DIV_ROUND_CLOSEST(usec * TIMER_FREQUENCY, USEC_PER_SEC) - 1;
 }
-- 
2.27.0