From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Kosuke Tatsukawa <tatsu-ab1@nec.com>
Subject: [PATCH 4.9 25/34] n_tty: wake up poll(POLLRDNORM) on receiving data
Date: Mon, 14 Feb 2022 10:25:51 +0100 [thread overview]
Message-ID: <20220214092446.757731373@linuxfoundation.org> (raw)
In-Reply-To: <20220214092445.946718557@linuxfoundation.org>
From: TATSUKAWA KOSUKE (立川 江介) <tatsu-ab1@nec.com>
commit c816b2e65b0e86b95011418cad334f0524fc33b8 upstream.
The poll man page says POLLRDNORM is equivalent to POLLIN when used as
an event.
$ man poll
<snip>
POLLRDNORM
Equivalent to POLLIN.
However, in n_tty driver, POLLRDNORM does not return until timeout even
if there is terminal input, whereas POLLIN returns.
The following test program works until kernel-3.17, but the test stops
in poll() after commit 57087d515441 ("tty: Fix spurious poll() wakeups").
[Steps to run test program]
$ cc -o test-pollrdnorm test-pollrdnorm.c
$ ./test-pollrdnorm
foo <-- Type in something from the terminal followed by [RET].
The string should be echoed back.
------------------------< test-pollrdnorm.c >------------------------
#include <stdio.h>
#include <errno.h>
#include <poll.h>
#include <unistd.h>
void main(void)
{
int n;
unsigned char buf[8];
struct pollfd fds[1] = {{ 0, POLLRDNORM, 0 }};
n = poll(fds, 1, -1);
if (n < 0)
perror("poll");
n = read(0, buf, 8);
if (n < 0)
perror("read");
if (n > 0)
write(1, buf, n);
}
------------------------------------------------------------------------
The attached patch fixes this problem. Many calls to
wake_up_interruptible_poll() in the kernel source code already specify
"POLLIN | POLLRDNORM".
Fixes: 57087d515441 ("tty: Fix spurious poll() wakeups")
Cc: stable@vger.kernel.org
Signed-off-by: Kosuke Tatsukawa <tatsu-ab1@nec.com>
Link: https://lore.kernel.org/r/TYCPR01MB81901C0F932203D30E452B3EA5209@TYCPR01MB8190.jpnprd01.prod.outlook.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/n_tty.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1377,7 +1377,7 @@ handle_newline:
put_tty_queue(c, ldata);
smp_store_release(&ldata->canon_head, ldata->read_head);
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
- wake_up_interruptible_poll(&tty->read_wait, POLLIN);
+ wake_up_interruptible_poll(&tty->read_wait, POLLIN | POLLRDNORM);
return 0;
}
}
@@ -1658,7 +1658,7 @@ static void __receive_buf(struct tty_str
if (read_cnt(ldata)) {
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
- wake_up_interruptible_poll(&tty->read_wait, POLLIN);
+ wake_up_interruptible_poll(&tty->read_wait, POLLIN | POLLRDNORM);
}
}
next prev parent reply other threads:[~2022-02-14 9:30 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-14 9:25 [PATCH 4.9 00/34] 4.9.302-rc1 review Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 01/34] integrity: check the return value of audit_log_start() Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 02/34] ima: Remove ima_policy file before directory Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 03/34] NFS: Fix initialisation of nfs_client cl_flags field Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 04/34] NFSD: Clamp WRITE offsets Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 05/34] Input: i8042 - Fix misplaced backport of "add ASUS Zenbook Flip to noselftest list" Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 06/34] serial: sh-sci: Fix misplaced backport of "Fix late enablement of AUTORTS" Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 07/34] ALSA: line6: Fix misplaced backport of "Fix wrong altsetting for LINE6_PODHD500_1" Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 08/34] Revert "net: axienet: Wait for PhyRstCmplt after core reset" Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 09/34] NFSv4 only print the label when its queried Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 10/34] nfs: nfs4clinet: check the return value of kstrdup() Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 11/34] NFSv4 remove zero number of fs_locations entries error check Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 12/34] scsi: target: iscsi: Make sure the np under each tpg is unique Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 13/34] usb: dwc2: gadget: dont try to disable ep0 in dwc2_hsotg_suspend Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 14/34] ARM: dts: imx23-evk: Remove MX23_PAD_SSP1_DETECT from hog group Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 15/34] staging: fbtft: Fix error path in fbtft_driver_module_init() Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 16/34] ARM: dts: imx6qdl-udoo: Properly describe the SD card detect Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 17/34] bonding: pair enable_port with slave_arr_updates Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 18/34] ipmr,ip6mr: acquire RTNL before calling ip[6]mr_free_table() on failure path Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 19/34] net: do not keep the dst cache when uncloning an skb dst and its metadata Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 20/34] net: fix a memleak " Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 21/34] tipc: rate limit warning for received illegal binding update Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 22/34] vt_ioctl: fix array_index_nospec in vt_setactivate Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 23/34] vt_ioctl: add array_index_nospec to VT_ACTIVATE Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 24/34] bpf: Add kconfig knob for disabling unpriv bpf by default Greg Kroah-Hartman
2022-02-14 9:25 ` Greg Kroah-Hartman [this message]
2022-02-14 9:25 ` [PATCH 4.9 26/34] usb: dwc3: gadget: Prevent core from processing stale TRBs Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 27/34] USB: gadget: validate interface OS descriptor requests Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 28/34] usb: gadget: rndis: check size of RNDIS_MSG_SET command Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 29/34] USB: serial: ftdi_sio: add support for Brainboxes US-159/235/320 Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 30/34] USB: serial: option: add ZTE MF286D modem Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 31/34] USB: serial: ch341: add support for GW Instek USB2.0-Serial devices Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 32/34] USB: serial: cp210x: add NCR Retail IO box id Greg Kroah-Hartman
2022-02-14 9:25 ` [PATCH 4.9 33/34] USB: serial: cp210x: add CPI Bulk Coin Recycler id Greg Kroah-Hartman
2022-02-14 9:26 ` [PATCH 4.9 34/34] hwmon: (dell-smm) Speed up setting of fan speed Greg Kroah-Hartman
2022-02-14 19:50 ` [PATCH 4.9 00/34] 4.9.302-rc1 review Florian Fainelli
2022-02-14 20:37 ` Slade Watkins
2022-02-14 22:33 ` Shuah Khan
2022-02-15 1:50 ` Guenter Roeck
2022-02-15 10:36 ` Naresh Kamboju
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