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From: Benjamin Berg <benjamin@sipsolutions.net>
To: linux-um@lists.infradead.org
Cc: Benjamin Berg <benjamin@sipsolutions.net>
Subject: [PATCH 08/27] um: Reap winch thread if it fails
Date: Wed,  3 Mar 2021 16:55:04 +0100	[thread overview]
Message-ID: <20210303155523.124277-9-benjamin@sipsolutions.net> (raw)
In-Reply-To: <20210303155523.124277-1-benjamin@sipsolutions.net>

When the winch thread runs into an error condition, it would exit(1) and
never be reaped until shutdown time. Change this to write a command byte
which causes the driver to kill it, therefore reaping the child.

Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
---
 arch/um/drivers/chan_user.c | 15 ++++++++++-----
 arch/um/drivers/line.c      | 13 ++++++++-----
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/arch/um/drivers/chan_user.c b/arch/um/drivers/chan_user.c
index 9d87c9998741..57547bdcb5c6 100644
--- a/arch/um/drivers/chan_user.c
+++ b/arch/um/drivers/chan_user.c
@@ -141,7 +141,7 @@ struct winch_data {
 	int pipe_fd;
 };
 
-static int winch_thread(void *arg)
+static __noreturn int winch_thread(void *arg)
 {
 	struct winch_data *data = arg;
 	sigset_t sigs;
@@ -168,7 +168,7 @@ static int winch_thread(void *arg)
 	if (sigprocmask(SIG_SETMASK, &sigs, NULL) < 0) {
 		os_info("winch_thread : sigprocmask failed, errno = %d\n",
 			errno);
-		exit(1);
+		goto wait_kill;
 	}
 	/* In sigsuspend(), block anything else than SIGWINCH. */
 	sigdelset(&sigs, SIGWINCH);
@@ -176,19 +176,19 @@ static int winch_thread(void *arg)
 	if (setsid() < 0) {
 		os_info("winch_thread : setsid failed, errno = %d\n",
 		       errno);
-		exit(1);
+		goto wait_kill;
 	}
 
 	if (ioctl(pty_fd, TIOCSCTTY, 0) < 0) {
 		os_info("winch_thread : TIOCSCTTY failed on "
 			"fd %d err = %d\n", pty_fd, errno);
-		exit(1);
+		goto wait_kill;
 	}
 
 	if (tcsetpgrp(pty_fd, os_getpid()) < 0) {
 		os_info("winch_thread : tcsetpgrp failed on fd %d err = %d\n",
 			pty_fd, errno);
-		exit(1);
+		goto wait_kill;
 	}
 
 	/*
@@ -214,6 +214,11 @@ static int winch_thread(void *arg)
 			os_info("winch_thread : write failed, err = %d\n",
 				errno);
 	}
+
+wait_kill:
+	c = 2;
+	count = write(pipe_fd, &c, sizeof(c));
+	while (1) { pause(); };
 }
 
 static int winch_tramp(int fd, struct tty_port *port, int *fd_out,
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 1c70a31e7c5b..b2800a085a3b 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -629,15 +629,18 @@ static irqreturn_t winch_interrupt(int irq, void *data)
 
 	if (fd != -1) {
 		err = generic_read(fd, &c, NULL);
-		if (err < 0) {
+		/* A read of 2 means the winch thread failed and has warned */
+		if (err < 0 || (err = 1 && c == 2)) {
 			if (err != -EAGAIN) {
 				winch->fd = -1;
 				list_del(&winch->list);
 				os_close_file(fd);
-				printk(KERN_ERR "winch_interrupt : "
-				       "read failed, errno = %d\n", -err);
-				printk(KERN_ERR "fd %d is losing SIGWINCH "
-				       "support\n", winch->tty_fd);
+				if (err < 0) {
+					printk(KERN_ERR "winch_interrupt : read failed, errno = %d\n",
+					       -err);
+					printk(KERN_ERR "fd %d is losing SIGWINCH support\n",
+					       winch->tty_fd);
+				}
 				INIT_WORK(&winch->work, __free_winch);
 				schedule_work(&winch->work);
 				return IRQ_HANDLED;
-- 
2.29.2


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  parent reply	other threads:[~2021-03-03 15:56 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-03 15:54 [PATCH 00/27] Implement SECCOMP based userland Benjamin Berg
2021-03-03 15:54 ` [PATCH 01/27] um: Switch printk calls to adhere to correct coding style Benjamin Berg
2021-03-03 15:54 ` [PATCH 02/27] um: Declare fix_range_common as a static function Benjamin Berg
2021-03-03 15:54 ` [PATCH 03/27] um: Drop support for hosts without SYSEMU_SINGLESTEP support Benjamin Berg
2021-06-19 20:17   ` Richard Weinberger
2021-06-20 12:05     ` Benjamin Berg
2021-03-03 15:55 ` [PATCH 04/27] um: Drop NULL check from start_userspace Benjamin Berg
2021-03-03 15:55 ` [PATCH 05/27] um: Make errors to stop ptraced child fatal during startup Benjamin Berg
2021-03-03 15:55 ` [PATCH 06/27] um: Don't use vfprintf() for os_info() Benjamin Berg
2021-03-03 15:55 ` [PATCH 07/27] um: Do not use printk in SIGWINCH helper thread Benjamin Berg
2021-03-03 15:55 ` Benjamin Berg [this message]
2021-03-03 15:55 ` [PATCH 09/27] um: Do not use printk in userspace trampoline Benjamin Berg
2021-03-03 15:55 ` [PATCH 10/27] um: Always inline stub functions Benjamin Berg
2021-03-03 15:55 ` [PATCH 11/27] um: Rely on PTRACE_SETREGSET to set FS/GS base registers Benjamin Berg
2021-03-03 15:55 ` [PATCH 12/27] um: Remove unused register save/restore functions Benjamin Berg
2021-03-03 15:55 ` [PATCH 13/27] um: Mark 32bit syscall helpers as clobbering memory Benjamin Berg
2021-03-03 15:55 ` [PATCH 14/27] um: Create signal stack memory assignment in stub_data Benjamin Berg
2021-03-03 15:55 ` [PATCH 15/27] um: Add generic stub_syscall6 function Benjamin Berg
2021-03-03 15:55 ` [PATCH 16/27] um: Rework syscall handling Benjamin Berg
2021-03-03 15:55 ` [PATCH 17/27] um: Store full CSGSFS and SS register from mcontext Benjamin Berg
2021-03-03 15:55 ` [PATCH 18/27] um: Pass full mm_id to functions creating helper processes Benjamin Berg
2021-03-03 15:55 ` [PATCH 19/27] um: Move faultinfo extraction into userspace routine Benjamin Berg
2021-03-03 15:55 ` [PATCH 20/27] um: Use struct uml_pt_regs for copy_context_skas0 Benjamin Berg
2021-03-03 15:55 ` [PATCH 21/27] um: Add UML_SECCOMP configuration option Benjamin Berg
2021-03-03 15:55 ` [PATCH 22/27] um: Add stub side of SECCOMP/futex based process handling Benjamin Berg
2021-03-03 15:55 ` [PATCH 23/27] um: Add helper functions to get/set state for SECCOMP Benjamin Berg
2021-03-03 15:55 ` [PATCH 24/27] um: Add SECCOMP support detection and initialization Benjamin Berg
2021-03-03 15:55 ` [PATCH 25/27] um: Die if a child dies unexpectedly in seccomp mode Benjamin Berg
2021-03-03 15:55 ` [PATCH 26/27] um: Implement kernel side of SECCOMP based process handling Benjamin Berg
2021-03-03 15:55 ` [PATCH 27/27] um: Delay flushing syscalls until the thread is restarted Benjamin Berg

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