netdev - Re: [PATCH v2 4/4] wcn36xx: Add debugfs entry to read firmware feature strings

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Message-ID: <87k07yq230.fsf@kernel.org>
Date:   Wed, 27 Jul 2022 13:31:15 +0300
From:   Kalle Valo <kvalo@...nel.org>
To:     Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc:     loic.poulain@...aro.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, wcn36xx@...ts.infradead.org,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v2 4/4] wcn36xx: Add debugfs entry to read firmware feature strings

Bryan O'Donoghue <bryan.odonoghue@...aro.org> writes:

> Add in the ability to easily find the firmware feature bits reported in the
> get feature exchange without having to compile-in debug prints.
>
> root@...aro-alip:~# cat /sys/kernel/debug/ieee80211/phy0/wcn36xx/firmware_feat_caps
> MCC
> P2P
> DOT11AC
> SLM_SESSIONIZATION
> DOT11AC_OPMODE
> SAP32STA
> TDLS
> P2P_GO_NOA_DECOUPLE_INIT_SCAN
> WLANACTIVE_OFFLOAD
> BEACON_OFFLOAD
> SCAN_OFFLOAD
> BCN_MISS_OFFLOAD
> STA_POWERSAVE
> STA_ADVANCED_PWRSAVE
> BCN_FILTER
> RTT
> RATECTRL
> WOW
> WLAN_ROAM_SCAN_OFFLOAD
> SPECULATIVE_PS_POLL
> IBSS_HEARTBEAT_OFFLOAD
> WLAN_SCAN_OFFLOAD
> WLAN_PERIODIC_TX_PTRN
> ADVANCE_TDLS
> BATCH_SCAN
> FW_IN_TX_PATH
> EXTENDED_NSOFFLOAD_SLOT
> CH_SWITCH_V1
> HT40_OBSS_SCAN
> UPDATE_CHANNEL_LIST
> WLAN_MCADDR_FLT
> WLAN_CH144
> TDLS_SCAN_COEXISTENCE
> LINK_LAYER_STATS_MEAS
> MU_MIMO
> EXTENDED_SCAN
> DYNAMIC_WMM_PS
> MAC_SPOOFED_SCAN
> FW_STATS
> WPS_PRBRSP_TMPL
> BCN_IE_FLT_DELTA
>
> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>

[...]

> +static ssize_t read_file_firmware_feature_caps(struct file *file,
> +					       char __user *user_buf,
> +					       size_t count, loff_t *ppos)
> +{
> +	struct wcn36xx *wcn = file->private_data;
> +	unsigned long page = get_zeroed_page(GFP_KERNEL);
> +	char *p = (char *)page;
> +	int i;
> +	int ret;
> +
> +	if (!p)
> +		return -ENOMEM;
> +
> +	mutex_lock(&wcn->hal_mutex);
> +	for (i = 0; i < MAX_FEATURE_SUPPORTED; i++) {
> +		if (wcn36xx_firmware_get_feat_caps(wcn->fw_feat_caps, i)) {
> +			p += sprintf(p, "%s\n",
> +				     wcn36xx_firmware_get_cap_name(i));
> +		}
> +	}
> +	mutex_unlock(&wcn->hal_mutex);
> +
> +	ret = simple_read_from_buffer(user_buf, count, ppos, (char *)page,
> +				      (unsigned long)p - page);
> +
> +	free_page(page);
> +	return ret;
> +}

Why not use the normal use kzalloc() and kfree()? That way you would not
need a separate page variable. What's the benefit from
get_zeroed_page()?

Also I don't see any checks for a memory allocation failure.

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