From e24328974a88aa8541e94e8bb8dfa2ade1b3c45d Mon Sep 17 00:00:00 2001 From: Donggeun Yoo Date: Wed, 2 Sep 2026 00:21:26 +0900 Subject: iio: proximity: vl53l0x-i2c: claim direct mode for raw reads vl53l0x_read_raw() starts a single-shot ranging measurement and reads back the result. Once the triggered buffer is enabled the sensor runs in continuous mode and its data-ready interrupt is routed to the trigger, so a concurrent in_distance_raw read disturbs the streaming setup and never gets its completion, returning -ETIMEDOUT. The original submission claimed direct mode here, but it was dropped during review because the driver had no buffer support at the time [1]. Continuous (buffered) mode was later added without restoring the claim [2], reintroducing the conflict. Reject direct reads while buffered capture is active by claiming direct mode around the measurement, as the vl53l1x sibling already does. Fixes: 762186c6e7b1 ("iio: proximity: vl53l0x-i2c: Added continuous mode support") Link: https://lore.kernel.org/linux-iio/20180911160300.GA9212@himanshu-Vostro-3559/ [1] Link: https://lore.kernel.org/linux-iio/20240909101508.263085-3-abhashkumarjha123@gmail.com/ [2] Signed-off-by: Donggeun Yoo Cc: stable@vger.kernel.org Signed-off-by: Jonathan Cameron --- Documentation/networking/ipsec.rst | 46 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 Documentation/networking/ipsec.rst (limited to 'Documentation/networking/ipsec.rst') diff --git a/Documentation/networking/ipsec.rst b/Documentation/networking/ipsec.rst new file mode 100644 index 000000000..afe9d7b48 --- /dev/null +++ b/Documentation/networking/ipsec.rst @@ -0,0 +1,46 @@ +.. SPDX-License-Identifier: GPL-2.0 + +===== +IPsec +===== + + +Here documents known IPsec corner cases which need to be keep in mind when +deploy various IPsec configuration in real world production environment. + +1. IPcomp: + Small IP packet won't get compressed at sender, and failed on + policy check on receiver. + +Quote from RFC3173:: + + 2.2. Non-Expansion Policy + + If the total size of a compressed payload and the IPComp header, as + defined in section 3, is not smaller than the size of the original + payload, the IP datagram MUST be sent in the original non-compressed + form. To clarify: If an IP datagram is sent non-compressed, no + + IPComp header is added to the datagram. This policy ensures saving + the decompression processing cycles and avoiding incurring IP + datagram fragmentation when the expanded datagram is larger than the + MTU. + + Small IP datagrams are likely to expand as a result of compression. + Therefore, a numeric threshold should be applied before compression, + where IP datagrams of size smaller than the threshold are sent in the + original form without attempting compression. The numeric threshold + is implementation dependent. + +Current IPComp implementation is indeed by the book, while as in practice +when sending non-compressed packet to the peer (whether or not packet len +is smaller than the threshold or the compressed len is larger than original +packet len), the packet is dropped when checking the policy as this packet +matches the selector but not coming from any XFRM layer, i.e., with no +security path. Such naked packet will not eventually make it to upper layer. +The result is much more wired to the user when ping peer with different +payload length. + +One workaround is try to set "level use" for each policy if user observed +above scenario. The consequence of doing so is small packet(uncompressed) +will skip policy checking on receiver side. -- cgit v1.3.1