Bryan O'Donoghue [off-list ref] 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@linaro-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@linaro.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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