For historical reasons, NEW_WIPHY messages generated by dumps or
GET_WIPHY commands were limited to 4096 bytes due to userspace tools
using limited buffers. Once the sizes NEW_WIPHY messages exceeded these
sizes, split dumps were introduced. All any non-legacy data was added
only to messages using split-dumps (including filtered dumps).
However, split-dumping has quite a significant overhead. On cards
tested, split dumps generated message sizes 1.7-1.8x compared to
non-split dumps, while still comfortably fitting into an 8k buffer. The
kernel now expects userspace to provide 16k buffers by default, and 32k
buffers are possible.
Introduce a concept of a large message, so that if the kernel detects
that userspace has provided a buffer of sufficient size, a non-split
message could be generated.
Signed-off-by: Denis Kenzior <denk...@gmail.com>
---
net/wireless/nl80211.c | 51 ++++++++++++++++++++++++++++++------------
1 file changed, 37 insertions(+), 14 deletions(-)
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index b9b0199b5ec6..682a095415eb 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -1839,6 +1839,7 @@ struct nl80211_dump_wiphy_state {
long start;
long split_start, band_start, chan_start, capa_start;
bool split;
+ bool large_message;
};
static int nl80211_send_wiphy(struct cfg80211_registered_device *rdev,
@@ -2027,7 +2028,8 @@ static int nl80211_send_wiphy(struct
cfg80211_registered_device *rdev,
if (nl80211_msg_put_channel(
msg, &rdev->wiphy, chan,
- state->split))
+ state->split ||
+ state->large_message))
goto nla_put_failure;
nla_nest_end(msg, nl_freq);
@@ -2072,7 +2074,7 @@ static int nl80211_send_wiphy(struct
cfg80211_registered_device *rdev,
i = nl80211_add_commands_unsplit(rdev, msg);
if (i < 0)
goto nla_put_failure;
- if (state->split) {
+ if (state->split || state->large_message) {
CMD(crit_proto_start, CRIT_PROTOCOL_START);
CMD(crit_proto_stop, CRIT_PROTOCOL_STOP);
if (rdev->wiphy.flags & WIPHY_FLAG_HAS_CHANNEL_SWITCH)
@@ -2111,7 +2113,8 @@ static int nl80211_send_wiphy(struct
cfg80211_registered_device *rdev,
/* fall through */
case 6:
#ifdef CONFIG_PM
- if (nl80211_send_wowlan(msg, rdev, state->split))
+ if (nl80211_send_wowlan(msg, rdev,
+ state->split || state->large_message))
goto nla_put_failure;
state->split_start++;
if (state->split)
@@ -2126,7 +2129,8 @@ static int nl80211_send_wiphy(struct
cfg80211_registered_device *rdev,
goto nla_put_failure;
if (nl80211_put_iface_combinations(&rdev->wiphy, msg,
- state->split))
+ state->split ||
+ state->large_message))
goto nla_put_failure;
state->split_start++;
@@ -2145,7 +2149,7 @@ static int nl80211_send_wiphy(struct
cfg80211_registered_device *rdev,
* dump is split, otherwise it makes it too big. Therefore
* only advertise it in that case.
*/
- if (state->split)
+ if (state->split || state->large_message)
features |= NL80211_FEATURE_ADVERTISE_CHAN_LIMITS;
if (nla_put_u32(msg, NL80211_ATTR_FEATURE_FLAGS, features))
goto nla_put_failure;
@@ -2170,13 +2174,20 @@ static int nl80211_send_wiphy(struct
cfg80211_registered_device *rdev,
*
* We still increment split_start so that in the split
* case we'll continue with more data in the next round,
- * but break unconditionally so unsplit data stops here.
+ * but break unless large_messages are requested, so
+ * legacy unsplit data stops here.
*/
state->split_start++;
- if (!state->split)
+ if (state->split)
+ break;
+
+ if (!state->large_message) {
state->split_start = 0;
- break;
+ break;
+ }
+
+ /* Fall through */
case 9:
if (rdev->wiphy.extended_capabilities &&
(nla_put(msg, NL80211_ATTR_EXT_CAPA,
@@ -2218,7 +2229,9 @@ static int nl80211_send_wiphy(struct
cfg80211_registered_device *rdev,
}
state->split_start++;
- break;
+ if (state->split)
+ break;
+ /* Fall through */
case 10:
if (nl80211_send_coalesce(msg, rdev))
goto nla_put_failure;
@@ -2234,7 +2247,9 @@ static int nl80211_send_wiphy(struct
cfg80211_registered_device *rdev,
goto nla_put_failure;
state->split_start++;
- break;
+ if (state->split)
+ break;
+ /* Fall through */
case 11:
if (rdev->wiphy.n_vendor_commands) {
const struct nl80211_vendor_cmd_info *info;
@@ -2270,7 +2285,9 @@ static int nl80211_send_wiphy(struct
cfg80211_registered_device *rdev,
nla_nest_end(msg, nested);
}
state->split_start++;
- break;
+ if (state->split)
+ break;
+ /* Fall through */
case 12:
if (rdev->wiphy.flags & WIPHY_FLAG_HAS_CHANNEL_SWITCH &&
nla_put_u8(msg, NL80211_ATTR_MAX_CSA_COUNTERS,
@@ -2312,7 +2329,9 @@ static int nl80211_send_wiphy(struct
cfg80211_registered_device *rdev,
}
state->split_start++;
- break;
+ if (state->split)
+ break;
+ /* Fall through */
case 13:
if (rdev->wiphy.num_iftype_ext_capab &&
rdev->wiphy.iftype_ext_capab) {
@@ -2380,13 +2399,17 @@ static int nl80211_send_wiphy(struct
cfg80211_registered_device *rdev,
}
state->split_start++;
- break;
+ if (state->split)
+ break;
+ /* Fall through */
case 14:
if (nl80211_send_pmsr_capa(rdev, msg))
goto nla_put_failure;
state->split_start++;
- break;
+ if (state->split)
+ break;
+ /* Fall through */
case 15:
if (rdev->wiphy.akm_suites &&
nla_put(msg, NL80211_ATTR_AKM_SUITES,
--
2.21.0
