From dd05add7b2b6004c5fa3a1f276f56d8668f86b65 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Sat, 26 Sep 2026 19:20:30 -0300 Subject: netfs: zero the tail of a short DIO/unbuffered read The buffered read collector zero-fills the tail of a short read that stops below the inode's i_size (netfs_clear_unread()), so a read that races an extending write still returns the expected number of bytes. The non-buffered collector path does no such thing: it just records how much was transferred. Add the same zero-fill for the non-buffered case, gated on NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short result from it is known to be safe to treat as a hole, as opposed to NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of the file and should be reported short as-is. Only CLEAR_TAIL should zero-fill here; a real EOF must stay a real short read. No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest, so this is inert on its own -- a following change teaches cifs to set it in the one case that needs it. Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item") Reviewed-by: David Howells Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: Christian Brauner Cc: Matthew Wilcox Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org --- drivers/rpmsg/rpmsg_ns.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 drivers/rpmsg/rpmsg_ns.c (limited to 'drivers/rpmsg/rpmsg_ns.c') diff --git a/drivers/rpmsg/rpmsg_ns.c b/drivers/rpmsg/rpmsg_ns.c new file mode 100644 index 000000000..bde8c8d43 --- /dev/null +++ b/drivers/rpmsg/rpmsg_ns.c @@ -0,0 +1,124 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) STMicroelectronics 2020 - All Rights Reserved + */ +#include +#include +#include +#include +#include +#include + +#include "rpmsg_internal.h" + +/** + * rpmsg_ns_register_device() - register name service device based on rpdev + * @rpdev: prepared rpdev to be used for creating endpoints + * + * This function wraps rpmsg_register_device() preparing the rpdev for use as + * basis for the rpmsg name service device. + */ +int rpmsg_ns_register_device(struct rpmsg_device *rpdev) +{ + rpdev->src = RPMSG_NS_ADDR; + rpdev->dst = RPMSG_NS_ADDR; + + return rpmsg_register_device_override(rpdev, "rpmsg_ns"); +} +EXPORT_SYMBOL(rpmsg_ns_register_device); + +/* invoked when a name service announcement arrives */ +static int rpmsg_ns_cb(struct rpmsg_device *rpdev, void *data, int len, + void *priv, u32 src) +{ + struct rpmsg_ns_msg *msg = data; + struct rpmsg_device *newch; + struct rpmsg_channel_info chinfo; + struct device *dev = rpdev->dev.parent; + int ret; + +#if defined(CONFIG_DYNAMIC_DEBUG) + dynamic_hex_dump("NS announcement: ", DUMP_PREFIX_NONE, 16, 1, + data, len, true); +#endif + + if (len != sizeof(*msg)) { + dev_err(dev, "malformed ns msg (%d)\n", len); + return -EINVAL; + } + + /* don't trust the remote processor for null terminating the name */ + msg->name[RPMSG_NAME_SIZE - 1] = '\0'; + + strscpy_pad(chinfo.name, msg->name, sizeof(chinfo.name)); + chinfo.src = RPMSG_ADDR_ANY; + chinfo.dst = rpmsg32_to_cpu(rpdev, msg->addr); + + dev_info(dev, "%sing channel %s addr 0x%x\n", + rpmsg32_to_cpu(rpdev, msg->flags) & RPMSG_NS_DESTROY ? + "destroy" : "creat", msg->name, chinfo.dst); + + if (rpmsg32_to_cpu(rpdev, msg->flags) & RPMSG_NS_DESTROY) { + ret = rpmsg_release_channel(rpdev, &chinfo); + if (ret) + dev_err(dev, "rpmsg_destroy_channel failed: %d\n", ret); + } else { + newch = rpmsg_create_channel(rpdev, &chinfo); + if (!newch) + dev_err(dev, "rpmsg_create_channel failed\n"); + } + + return 0; +} + +static int rpmsg_ns_probe(struct rpmsg_device *rpdev) +{ + struct rpmsg_endpoint *ns_ept; + struct rpmsg_channel_info ns_chinfo = { + .src = RPMSG_NS_ADDR, + .dst = RPMSG_NS_ADDR, + .name = "name_service", + }; + + /* + * Create the NS announcement service endpoint associated to the RPMsg + * device. The endpoint will be automatically destroyed when the RPMsg + * device will be deleted. + */ + ns_ept = rpmsg_create_ept(rpdev, rpmsg_ns_cb, NULL, ns_chinfo); + if (!ns_ept) { + dev_err(&rpdev->dev, "failed to create the ns ept\n"); + return -ENOMEM; + } + rpdev->ept = ns_ept; + + return 0; +} + +static struct rpmsg_driver rpmsg_ns_driver = { + .drv.name = KBUILD_MODNAME, + .probe = rpmsg_ns_probe, +}; + +static int rpmsg_ns_init(void) +{ + int ret; + + ret = register_rpmsg_driver(&rpmsg_ns_driver); + if (ret < 0) + pr_err("%s: Failed to register rpmsg driver\n", __func__); + + return ret; +} +postcore_initcall(rpmsg_ns_init); + +static void rpmsg_ns_exit(void) +{ + unregister_rpmsg_driver(&rpmsg_ns_driver); +} +module_exit(rpmsg_ns_exit); + +MODULE_DESCRIPTION("Name service announcement rpmsg driver"); +MODULE_AUTHOR("Arnaud Pouliquen "); +MODULE_ALIAS("rpmsg:" KBUILD_MODNAME); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1