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/acpi/hed.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) create mode 100644 drivers/acpi/hed.c (limited to 'drivers/acpi/hed.c') diff --git a/drivers/acpi/hed.c b/drivers/acpi/hed.c new file mode 100644 index 000000000..48562f53d --- /dev/null +++ b/drivers/acpi/hed.c @@ -0,0 +1,90 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ACPI Hardware Error Device (PNP0C33) Driver + * + * Copyright (C) 2010, Intel Corp. + * Author: Huang Ying + * + * ACPI Hardware Error Device is used to report some hardware errors + * notified via SCI, mainly the corrected errors. + */ + +#include +#include +#include +#include +#include +#include + +static const struct acpi_device_id acpi_hed_ids[] = { + {"PNP0C33", 0}, + {"", 0}, +}; +MODULE_DEVICE_TABLE(acpi, acpi_hed_ids); + +static bool hed_present; + +static BLOCKING_NOTIFIER_HEAD(acpi_hed_notify_list); + +int register_acpi_hed_notifier(struct notifier_block *nb) +{ + return blocking_notifier_chain_register(&acpi_hed_notify_list, nb); +} +EXPORT_SYMBOL_GPL(register_acpi_hed_notifier); + +void unregister_acpi_hed_notifier(struct notifier_block *nb) +{ + blocking_notifier_chain_unregister(&acpi_hed_notify_list, nb); +} +EXPORT_SYMBOL_GPL(unregister_acpi_hed_notifier); + +/* + * SCI to report hardware error is forwarded to the listeners of HED, + * it is used by HEST Generic Hardware Error Source with notify type + * SCI. + */ +static void acpi_hed_notify(acpi_handle handle, u32 event, void *data) +{ + blocking_notifier_call_chain(&acpi_hed_notify_list, 0, NULL); +} + +static int acpi_hed_probe(struct platform_device *pdev) +{ + int err; + + /* Only one hardware error device */ + if (hed_present) + return -EINVAL; + + err = devm_acpi_install_notify_handler(&pdev->dev, ACPI_DEVICE_NOTIFY, + acpi_hed_notify, NULL); + if (err) + return err; + + hed_present = true; + return 0; +} + +static void acpi_hed_remove(struct platform_device *pdev) +{ + hed_present = false; +} + +static struct platform_driver acpi_hed_driver = { + .probe = acpi_hed_probe, + .remove = acpi_hed_remove, + .driver = { + .name = "acpi-hardware-error-device", + .acpi_match_table = acpi_hed_ids, + }, +}; + +static int __init acpi_hed_driver_init(void) +{ + return platform_driver_register(&acpi_hed_driver); +} +subsys_initcall(acpi_hed_driver_init); + +MODULE_AUTHOR("Huang Ying"); +MODULE_DESCRIPTION("ACPI Hardware Error Device Driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1