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/rtc/rtc-88pm886.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 96 insertions(+) create mode 100644 drivers/rtc/rtc-88pm886.c (limited to 'drivers/rtc/rtc-88pm886.c') diff --git a/drivers/rtc/rtc-88pm886.c b/drivers/rtc/rtc-88pm886.c new file mode 100644 index 000000000..71443ae1b --- /dev/null +++ b/drivers/rtc/rtc-88pm886.c @@ -0,0 +1,96 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include + +#include + +/* + * Time is calculated as the sum of a 32-bit read-only advancing counter and a + * writeable constant offset stored in the chip's spare registers. + */ + +static int pm886_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct regmap *regmap = dev_get_drvdata(dev); + u32 time; + u32 buf; + int ret; + + ret = regmap_bulk_read(regmap, PM886_REG_RTC_SPARE1, &buf, 4); + if (ret) + return ret; + time = buf; + + ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4); + if (ret) + return ret; + time += buf; + + rtc_time64_to_tm(time, tm); + + return 0; +} + +static int pm886_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct regmap *regmap = dev_get_drvdata(dev); + u32 buf; + int ret; + + ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4); + if (ret) + return ret; + + buf = rtc_tm_to_time64(tm) - buf; + + return regmap_bulk_write(regmap, PM886_REG_RTC_SPARE1, &buf, 4); +} + +static const struct rtc_class_ops pm886_rtc_ops = { + .read_time = pm886_rtc_read_time, + .set_time = pm886_rtc_set_time, +}; + +static int pm886_rtc_probe(struct platform_device *pdev) +{ + struct pm886_chip *chip = dev_get_drvdata(pdev->dev.parent); + struct device *dev = &pdev->dev; + struct rtc_device *rtc; + int ret; + + platform_set_drvdata(pdev, chip->regmap); + + rtc = devm_rtc_allocate_device(dev); + if (IS_ERR(rtc)) + return dev_err_probe(dev, PTR_ERR(rtc), + "Failed to allocate RTC device\n"); + + rtc->ops = &pm886_rtc_ops; + rtc->range_max = U32_MAX; + + ret = devm_rtc_register_device(rtc); + if (ret) + return dev_err_probe(dev, ret, "Failed to register RTC device\n"); + + return 0; +} + +static const struct platform_device_id pm886_rtc_id_table[] = { + { .name = "88pm886-rtc" }, + { } +}; +MODULE_DEVICE_TABLE(platform, pm886_rtc_id_table); + +static struct platform_driver pm886_rtc_driver = { + .driver = { + .name = "88pm886-rtc", + }, + .probe = pm886_rtc_probe, + .id_table = pm886_rtc_id_table, +}; +module_platform_driver(pm886_rtc_driver); + +MODULE_DESCRIPTION("Marvell 88PM886 RTC driver"); +MODULE_AUTHOR("Karel Balej "); +MODULE_LICENSE("GPL"); -- cgit v1.3.1