linux-kernel - Re: [PATCH] wifi: iwlwifi: pcie: ensure RX_QUEUE_CB

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Message-ID: <aEsrmH7sDVvsmgLs@monster>
Date: Thu, 12 Jun 2025 21:33:44 +0200
From: Anders Roxell <anders.roxell@...aro.org>
To: Johannes Berg <johannes@...solutions.net>
Cc: miriam.rachel.korenblit@...el.com, dan.carpenter@...aro.org,
	arnd@...db.de, linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Linux Kernel Functional Testing <lkft@...aro.org>
Subject: Re: [PATCH] wifi: iwlwifi: pcie: ensure RX_QUEUE_CB_SIZE fits
 bitfield for gcc-8|9

On 2025-06-12 17:21, Johannes Berg wrote:
> > 
> > diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/ctxt-info.c b/drivers/net/wireless/intel/iwlwifi/pcie/ctxt-info.c
> > index cb36baac14da..1854d071aff2 100644
> > --- a/drivers/net/wireless/intel/iwlwifi/pcie/ctxt-info.c
> > +++ b/drivers/net/wireless/intel/iwlwifi/pcie/ctxt-info.c
> > @@ -204,9 +204,10 @@ int iwl_pcie_ctxt_info_init(struct iwl_trans *trans,
> >  
> >  	WARN_ON(RX_QUEUE_CB_SIZE(iwl_trans_get_num_rbds(trans)) > 12);
> >  	control_flags = IWL_CTXT_INFO_TFD_FORMAT_LONG;
> > -	control_flags |=
> > -		u32_encode_bits(RX_QUEUE_CB_SIZE(iwl_trans_get_num_rbds(trans)),
> > -				IWL_CTXT_INFO_RB_CB_SIZE);
> > +	/* This should just be u32_encode_bits() but gcc-8 and gcc-9 fail to build */
> > +	control_flags |= FIELD_PREP(IWL_CTXT_INFO_RB_CB_SIZE,
> > +		RX_QUEUE_CB_SIZE(iwl_trans_get_num_rbds(trans)) &
> > +		FIELD_MAX(IWL_CTXT_INFO_RB_CB_SIZE));
> > 
> 
> The coding style is really confusing now though - what are arguments to
> the macro and all that.

Would it help if I indent like this?

diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/ctxt-info.c b/drivers/net/wireless/intel/iwlwifi/pcie/ctxt-info.c
index cb36baac14da..5bb81ed7db79 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/ctxt-info.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/ctxt-info.c
@@ -204,9 +204,10 @@ int iwl_pcie_ctxt_info_init(struct iwl_trans *trans,
 
 	WARN_ON(RX_QUEUE_CB_SIZE(iwl_trans_get_num_rbds(trans)) > 12);
 	control_flags = IWL_CTXT_INFO_TFD_FORMAT_LONG;
-	control_flags |=
-		u32_encode_bits(RX_QUEUE_CB_SIZE(iwl_trans_get_num_rbds(trans)),
-				IWL_CTXT_INFO_RB_CB_SIZE);
+	/* This should just be u32_encode_bits() but gcc-8 and gcc-9 fail to build */
+	control_flags |= FIELD_PREP(IWL_CTXT_INFO_RB_CB_SIZE,
+				    RX_QUEUE_CB_SIZE(iwl_trans_get_num_rbds(trans)) &
+				    FIELD_MAX(IWL_CTXT_INFO_RB_CB_SIZE));
 	control_flags |= u32_encode_bits(rb_size, IWL_CTXT_INFO_RB_SIZE);
 	ctxt_info->control.control_flags = cpu_to_le32(control_flags);
 

Cheers,
Anders