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-em3027.c | 158 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 158 insertions(+) create mode 100644 drivers/rtc/rtc-em3027.c (limited to 'drivers/rtc/rtc-em3027.c') diff --git a/drivers/rtc/rtc-em3027.c b/drivers/rtc/rtc-em3027.c new file mode 100644 index 000000000..d555e5d59 --- /dev/null +++ b/drivers/rtc/rtc-em3027.c @@ -0,0 +1,158 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * An rtc/i2c driver for the EM Microelectronic EM3027 + * Copyright 2011 CompuLab, Ltd. + * + * Author: Mike Rapoport + * + * Based on rtc-ds1672.c by Alessandro Zummo + */ + +#include +#include +#include +#include +#include + +/* Registers */ +#define EM3027_REG_ON_OFF_CTRL 0x00 +#define EM3027_REG_IRQ_CTRL 0x01 +#define EM3027_REG_IRQ_FLAGS 0x02 +#define EM3027_REG_STATUS 0x03 +#define EM3027_REG_RST_CTRL 0x04 + +#define EM3027_REG_WATCH_SEC 0x08 +#define EM3027_REG_WATCH_MIN 0x09 +#define EM3027_REG_WATCH_HOUR 0x0a +#define EM3027_REG_WATCH_DATE 0x0b +#define EM3027_REG_WATCH_DAY 0x0c +#define EM3027_REG_WATCH_MON 0x0d +#define EM3027_REG_WATCH_YEAR 0x0e + +#define EM3027_REG_ALARM_SEC 0x10 +#define EM3027_REG_ALARM_MIN 0x11 +#define EM3027_REG_ALARM_HOUR 0x12 +#define EM3027_REG_ALARM_DATE 0x13 +#define EM3027_REG_ALARM_DAY 0x14 +#define EM3027_REG_ALARM_MON 0x15 +#define EM3027_REG_ALARM_YEAR 0x16 + +static struct i2c_driver em3027_driver; + +static int em3027_get_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + + unsigned char addr = EM3027_REG_WATCH_SEC; + unsigned char buf[7]; + + struct i2c_msg msgs[] = { + {/* setup read addr */ + .addr = client->addr, + .len = 1, + .buf = &addr + }, + {/* read time/date */ + .addr = client->addr, + .flags = I2C_M_RD, + .len = 7, + .buf = buf + }, + }; + + /* read time/date registers */ + if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { + dev_err(&client->dev, "%s: read error\n", __func__); + return -EIO; + } + + tm->tm_sec = bcd2bin(buf[0]); + tm->tm_min = bcd2bin(buf[1]); + tm->tm_hour = bcd2bin(buf[2]); + tm->tm_mday = bcd2bin(buf[3]); + tm->tm_wday = bcd2bin(buf[4]); + tm->tm_mon = bcd2bin(buf[5]) - 1; + tm->tm_year = bcd2bin(buf[6]) + 100; + + return 0; +} + +static int em3027_set_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + unsigned char buf[8]; + + struct i2c_msg msg = { + .addr = client->addr, + .len = 8, + .buf = buf, /* write time/date */ + }; + + buf[0] = EM3027_REG_WATCH_SEC; + buf[1] = bin2bcd(tm->tm_sec); + buf[2] = bin2bcd(tm->tm_min); + buf[3] = bin2bcd(tm->tm_hour); + buf[4] = bin2bcd(tm->tm_mday); + buf[5] = bin2bcd(tm->tm_wday); + buf[6] = bin2bcd(tm->tm_mon + 1); + buf[7] = bin2bcd(tm->tm_year % 100); + + /* write time/date registers */ + if ((i2c_transfer(client->adapter, &msg, 1)) != 1) { + dev_err(&client->dev, "%s: write error\n", __func__); + return -EIO; + } + + return 0; +} + +static const struct rtc_class_ops em3027_rtc_ops = { + .read_time = em3027_get_time, + .set_time = em3027_set_time, +}; + +static int em3027_probe(struct i2c_client *client) +{ + struct rtc_device *rtc; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + rtc = devm_rtc_device_register(&client->dev, em3027_driver.driver.name, + &em3027_rtc_ops, THIS_MODULE); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + i2c_set_clientdata(client, rtc); + + return 0; +} + +static const struct i2c_device_id em3027_id[] = { + { .name = "em3027" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, em3027_id); + +#ifdef CONFIG_OF +static const struct of_device_id em3027_of_match[] = { + { .compatible = "emmicro,em3027", }, + {} +}; +MODULE_DEVICE_TABLE(of, em3027_of_match); +#endif + +static struct i2c_driver em3027_driver = { + .driver = { + .name = "rtc-em3027", + .of_match_table = of_match_ptr(em3027_of_match), + }, + .probe = em3027_probe, + .id_table = em3027_id, +}; + +module_i2c_driver(em3027_driver); + +MODULE_AUTHOR("Mike Rapoport "); +MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1