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/of/module.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 drivers/of/module.c (limited to 'drivers/of/module.c') diff --git a/drivers/of/module.c b/drivers/of/module.c new file mode 100644 index 000000000..1e735fc13 --- /dev/null +++ b/drivers/of/module.c @@ -0,0 +1,81 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Linux kernel module helpers. + */ + +#include +#include +#include +#include + +ssize_t of_modalias(const struct device_node *np, char *str, ssize_t len) +{ + const char *compat; + char *c; + struct property *p; + ssize_t csize; + ssize_t tsize; + + /* + * Prevent a kernel oops in vsnprintf() -- it only allows passing a + * NULL ptr when the length is also 0. Also filter out the negative + * lengths... + */ + if ((len > 0 && !str) || len < 0) + return -EINVAL; + + /* Name & Type */ + /* %p eats all alphanum characters, so %c must be used here */ + csize = snprintf(str, len, "of:N%pOFn%c%s", np, 'T', + of_node_get_device_type(np)); + tsize = csize; + if (csize >= len) + csize = len > 0 ? len - 1 : 0; + len -= csize; + str += csize; + + of_property_for_each_string(np, "compatible", p, compat) { + csize = snprintf(str, len, "C%s", compat); + tsize += csize; + if (csize >= len) + continue; + for (c = str; c; ) { + c = strchr(c, ' '); + if (c) + *c++ = '_'; + } + len -= csize; + str += csize; + } + + return tsize; +} + +int of_request_module(const struct device_node *np) +{ + char *str; + ssize_t size; + int ret; + + if (!np) + return -ENODEV; + + size = of_modalias(np, NULL, 0); + if (size < 0) + return size; + + /* Reserve an additional byte for the trailing '\0' */ + size++; + + str = kmalloc(size, GFP_KERNEL); + if (!str) + return -ENOMEM; + + of_modalias(np, str, size); + str[size - 1] = '\0'; + ret = request_module(str); + kfree(str); + + return ret; +} +EXPORT_SYMBOL_GPL(of_request_module); -- cgit v1.3.1