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-ds1672.c | 160 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 160 insertions(+) create mode 100644 drivers/rtc/rtc-ds1672.c (limited to 'drivers/rtc/rtc-ds1672.c') diff --git a/drivers/rtc/rtc-ds1672.c b/drivers/rtc/rtc-ds1672.c new file mode 100644 index 000000000..c610beb55 --- /dev/null +++ b/drivers/rtc/rtc-ds1672.c @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * An rtc/i2c driver for the Dallas DS1672 + * Copyright 2005-06 Tower Technologies + * + * Author: Alessandro Zummo + */ + +#include +#include +#include + +/* Registers */ + +#define DS1672_REG_CNT_BASE 0 +#define DS1672_REG_CONTROL 4 +#define DS1672_REG_TRICKLE 5 + +#define DS1672_REG_CONTROL_EOSC 0x80 + +/* + * In the routines that deal directly with the ds1672 hardware, we use + * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch + * Time is set to UTC. + */ +static int ds1672_read_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + unsigned long time; + unsigned char addr = DS1672_REG_CONTROL; + unsigned char buf[4]; + + struct i2c_msg msgs[] = { + {/* setup read ptr */ + .addr = client->addr, + .len = 1, + .buf = &addr + }, + {/* read date */ + .addr = client->addr, + .flags = I2C_M_RD, + .len = 1, + .buf = buf + }, + }; + + /* read control register */ + if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { + dev_warn(&client->dev, "Unable to read the control register\n"); + return -EIO; + } + + if (buf[0] & DS1672_REG_CONTROL_EOSC) { + dev_warn(&client->dev, "Oscillator not enabled. Set time to enable.\n"); + return -EINVAL; + } + + addr = DS1672_REG_CNT_BASE; + msgs[1].len = 4; + + /* read date registers */ + if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { + dev_err(&client->dev, "%s: read error\n", __func__); + return -EIO; + } + + dev_dbg(&client->dev, + "%s: raw read data - counters=%02x,%02x,%02x,%02x\n", + __func__, buf[0], buf[1], buf[2], buf[3]); + + time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) | + (buf[1] << 8) | buf[0]; + + rtc_time64_to_tm(time, tm); + + dev_dbg(&client->dev, "%s: tm is %ptR\n", __func__, tm); + + return 0; +} + +static int ds1672_set_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + int xfer; + unsigned char buf[6]; + unsigned long secs = rtc_tm_to_time64(tm); + + buf[0] = DS1672_REG_CNT_BASE; + buf[1] = secs & 0x000000FF; + buf[2] = (secs & 0x0000FF00) >> 8; + buf[3] = (secs & 0x00FF0000) >> 16; + buf[4] = (secs & 0xFF000000) >> 24; + buf[5] = 0; /* set control reg to enable counting */ + + xfer = i2c_master_send(client, buf, 6); + if (xfer != 6) { + dev_err(&client->dev, "%s: send: %d\n", __func__, xfer); + return -EIO; + } + + return 0; +} + +static const struct rtc_class_ops ds1672_rtc_ops = { + .read_time = ds1672_read_time, + .set_time = ds1672_set_time, +}; + +static int ds1672_probe(struct i2c_client *client) +{ + int err = 0; + struct rtc_device *rtc; + + dev_dbg(&client->dev, "%s\n", __func__); + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + rtc = devm_rtc_allocate_device(&client->dev); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + rtc->ops = &ds1672_rtc_ops; + rtc->range_max = U32_MAX; + + err = devm_rtc_register_device(rtc); + if (err) + return err; + + i2c_set_clientdata(client, rtc); + + return 0; +} + +static const struct i2c_device_id ds1672_id[] = { + { .name = "ds1672" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, ds1672_id); + +static const __maybe_unused struct of_device_id ds1672_of_match[] = { + { .compatible = "dallas,ds1672" }, + { } +}; +MODULE_DEVICE_TABLE(of, ds1672_of_match); + +static struct i2c_driver ds1672_driver = { + .driver = { + .name = "rtc-ds1672", + .of_match_table = of_match_ptr(ds1672_of_match), + }, + .probe = ds1672_probe, + .id_table = ds1672_id, +}; + +module_i2c_driver(ds1672_driver); + +MODULE_AUTHOR("Alessandro Zummo "); +MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1