From 276d9e82e06cade9c4d081664ad63da1be971642 Mon Sep 17 00:00:00 2001 From: Julius Niedworok Date: Thu, 28 Mar 2019 21:01:06 +0100 Subject: [PATCH] mac80211: debugfs option to force TX status frames At Technical University of Munich we use MAC 802.11 TX status frames to perform several measurements in MAC 802.11 setups. With ath based drivers this was possible until commit d94a461d7a7df6 ("ath9k: use ieee80211_tx_status_noskb where possible") as the driver ignored the IEEE80211_TX_CTL_REQ_TX_STATUS flag and always delivered tx_status frames. Since that commit, this behavior was changed and the driver now adheres to IEEE80211_TX_CTL_REQ_TX_STATUS. Due to performance reasons, IEEE80211_TX_CTL_REQ_TX_STATUS is not set for data frames from interfaces in managed mode. Hence, frames that are sent from a managed mode interface do never deliver tx_status frames. This remains true even if a monitor mode interface (the measurement interface) is added to the same ieee80211 physical device. Thus, there is no possibility for receiving tx_status frames for frames sent on an interface in managed mode, if the driver adheres to IEEE80211_TX_CTL_REQ_TX_STATUS. In order to force delivery of tx_status frames for research and debugging purposes, implement a debugfs option force_tx_status for ieee80211 physical devices. When this option is set for a physical device, IEEE80211_TX_CTL_REQ_TX_STATUS is enabled in all packets sent from that device. This option can be set via /sys/kernel/debug/ieee80211//force_tx_status. The default is disabled. Co-developed-by: Charlie Groh Signed-off-by: Charlie Groh Signed-off-by: Julius Niedworok Signed-off-by: Johannes Berg --- net/mac80211/debugfs.c | 53 ++++++++++++++++++++++++++++++++++++++ net/mac80211/ieee80211_i.h | 1 + net/mac80211/tx.c | 10 +++++++ 3 files changed, 64 insertions(+) diff --git a/net/mac80211/debugfs.c b/net/mac80211/debugfs.c index aa6f23e1a457..0d462206eef6 100644 --- a/net/mac80211/debugfs.c +++ b/net/mac80211/debugfs.c @@ -150,6 +150,58 @@ static const struct file_operations aqm_ops = { .llseek = default_llseek, }; +static ssize_t force_tx_status_read(struct file *file, + char __user *user_buf, + size_t count, + loff_t *ppos) +{ + struct ieee80211_local *local = file->private_data; + char buf[3]; + int len = 0; + + len = scnprintf(buf, sizeof(buf), "%d\n", (int)local->force_tx_status); + + return simple_read_from_buffer(user_buf, count, ppos, + buf, len); +} + +static ssize_t force_tx_status_write(struct file *file, + const char __user *user_buf, + size_t count, + loff_t *ppos) +{ + struct ieee80211_local *local = file->private_data; + char buf[3]; + size_t len; + + if (count > sizeof(buf)) + return -EINVAL; + + if (copy_from_user(buf, user_buf, count)) + return -EFAULT; + + buf[sizeof(buf) - 1] = '\0'; + len = strlen(buf); + if (len > 0 && buf[len - 1] == '\n') + buf[len - 1] = 0; + + if (buf[0] == '0' && buf[1] == '\0') + local->force_tx_status = 0; + else if (buf[0] == '1' && buf[1] == '\0') + local->force_tx_status = 1; + else + return -EINVAL; + + return count; +} + +static const struct file_operations force_tx_status_ops = { + .write = force_tx_status_write, + .read = force_tx_status_read, + .open = simple_open, + .llseek = default_llseek, +}; + #ifdef CONFIG_PM static ssize_t reset_write(struct file *file, const char __user *user_buf, size_t count, loff_t *ppos) @@ -383,6 +435,7 @@ void debugfs_hw_add(struct ieee80211_local *local) DEBUGFS_ADD(hwflags); DEBUGFS_ADD(user_power); DEBUGFS_ADD(power); + DEBUGFS_ADD_MODE(force_tx_status, 0600); if (local->ops->wake_tx_queue) DEBUGFS_ADD_MODE(aqm, 0600); diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index 32094e2ac0cb..5a0dedd31266 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -1384,6 +1384,7 @@ struct ieee80211_local { struct dentry *rcdir; struct dentry *keys; } debugfs; + bool force_tx_status; #endif /* diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 5a89733723e7..9426bcce95e7 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -2471,6 +2471,11 @@ static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata, if (IS_ERR(sta)) sta = NULL; +#ifdef CONFIG_MAC80211_DEBUGFS + if (local->force_tx_status) + info_flags |= IEEE80211_TX_CTL_REQ_TX_STATUS; +#endif + /* convert Ethernet header to proper 802.11 header (based on * operation mode) */ ethertype = (skb->data[12] << 8) | skb->data[13]; @@ -3473,6 +3478,11 @@ static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata, (tid_tx ? IEEE80211_TX_CTL_AMPDU : 0); info->control.flags = IEEE80211_TX_CTRL_FAST_XMIT; +#ifdef CONFIG_MAC80211_DEBUGFS + if (local->force_tx_status) + info->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS; +#endif + if (hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_QOS_DATA)) { tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK; *ieee80211_get_qos_ctl(hdr) = tid; -- 2.30.2