From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Tiwei Bie <tiwei.btw@antgroup.com>,
Johannes Berg <johannes.berg@intel.com>,
Sasha Levin <sashal@kernel.org>,
richard@nod.at, anton.ivanov@cambridgegreys.com,
johannes@sipsolutions.net, linux-um@lists.infradead.org
Subject: [PATCH AUTOSEL 6.14 25/31] um: Switch to the pthread-based helper in sigio workaround
Date: Mon, 7 Apr 2025 14:10:41 -0400 [thread overview]
Message-ID: <20250407181054.3177479-25-sashal@kernel.org> (raw)
In-Reply-To: <20250407181054.3177479-1-sashal@kernel.org>
From: Tiwei Bie <tiwei.btw@antgroup.com>
[ Upstream commit d295beeed2552a987796d627ba7d0985b1e2d72f ]
The write_sigio thread and UML kernel thread share the same errno,
which can lead to conflicts when both call syscalls concurrently.
Switch to the pthread-based helper to address this issue.
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20250319135523.97050-4-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/um/os-Linux/sigio.c | 44 +++++++++++++++++-----------------------
1 file changed, 19 insertions(+), 25 deletions(-)
diff --git a/arch/um/os-Linux/sigio.c b/arch/um/os-Linux/sigio.c
index 9aac8def4d635..61b348a2ea974 100644
--- a/arch/um/os-Linux/sigio.c
+++ b/arch/um/os-Linux/sigio.c
@@ -21,8 +21,7 @@
* Protected by sigio_lock(), also used by sigio_cleanup, which is an
* exitcall.
*/
-static int write_sigio_pid = -1;
-static unsigned long write_sigio_stack;
+static struct os_helper_thread *write_sigio_td;
/*
* These arrays are initialized before the sigio thread is started, and
@@ -48,15 +47,15 @@ static struct pollfds current_poll;
static struct pollfds next_poll;
static struct pollfds all_sigio_fds;
-static int write_sigio_thread(void *unused)
+static void *write_sigio_thread(void *unused)
{
struct pollfds *fds, tmp;
struct pollfd *p;
int i, n, respond_fd;
char c;
- os_set_pdeathsig();
- os_fix_helper_signals();
+ os_fix_helper_thread_signals();
+
fds = ¤t_poll;
while (1) {
n = poll(fds->poll, fds->used, -1);
@@ -98,7 +97,7 @@ static int write_sigio_thread(void *unused)
}
}
- return 0;
+ return NULL;
}
static int need_poll(struct pollfds *polls, int n)
@@ -152,11 +151,10 @@ static void update_thread(void)
return;
fail:
/* Critical section start */
- if (write_sigio_pid != -1) {
- os_kill_process(write_sigio_pid, 1);
- free_stack(write_sigio_stack, 0);
+ if (write_sigio_td) {
+ os_kill_helper_thread(write_sigio_td);
+ write_sigio_td = NULL;
}
- write_sigio_pid = -1;
close(sigio_private[0]);
close(sigio_private[1]);
close(write_sigio_fds[0]);
@@ -220,7 +218,7 @@ int __ignore_sigio_fd(int fd)
* sigio_cleanup has already run, then update_thread will hang
* or fail because the thread is no longer running.
*/
- if (write_sigio_pid == -1)
+ if (!write_sigio_td)
return -EIO;
for (i = 0; i < current_poll.used; i++) {
@@ -279,14 +277,14 @@ static void write_sigio_workaround(void)
int err;
int l_write_sigio_fds[2];
int l_sigio_private[2];
- int l_write_sigio_pid;
+ struct os_helper_thread *l_write_sigio_td;
/* We call this *tons* of times - and most ones we must just fail. */
sigio_lock();
- l_write_sigio_pid = write_sigio_pid;
+ l_write_sigio_td = write_sigio_td;
sigio_unlock();
- if (l_write_sigio_pid != -1)
+ if (l_write_sigio_td)
return;
err = os_pipe(l_write_sigio_fds, 1, 1);
@@ -312,7 +310,7 @@ static void write_sigio_workaround(void)
* Did we race? Don't try to optimize this, please, it's not so likely
* to happen, and no more than once at the boot.
*/
- if (write_sigio_pid != -1)
+ if (write_sigio_td)
goto out_free;
current_poll = ((struct pollfds) { .poll = p,
@@ -325,18 +323,15 @@ static void write_sigio_workaround(void)
memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
- write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
- CLONE_FILES | CLONE_VM,
- &write_sigio_stack);
-
- if (write_sigio_pid < 0)
+ err = os_run_helper_thread(&write_sigio_td, write_sigio_thread, NULL);
+ if (err < 0)
goto out_clear;
sigio_unlock();
return;
out_clear:
- write_sigio_pid = -1;
+ write_sigio_td = NULL;
write_sigio_fds[0] = -1;
write_sigio_fds[1] = -1;
sigio_private[0] = -1;
@@ -394,12 +389,11 @@ void maybe_sigio_broken(int fd)
static void sigio_cleanup(void)
{
- if (write_sigio_pid == -1)
+ if (!write_sigio_td)
return;
- os_kill_process(write_sigio_pid, 1);
- free_stack(write_sigio_stack, 0);
- write_sigio_pid = -1;
+ os_kill_helper_thread(write_sigio_td);
+ write_sigio_td = NULL;
}
__uml_exitcall(sigio_cleanup);
--
2.39.5
next prev parent reply other threads:[~2025-04-07 19:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20250407181054.3177479-1-sashal@kernel.org>
2025-04-07 18:10 ` [PATCH AUTOSEL 6.14 23/31] um: work around sched_yield not yielding in time-travel mode Sasha Levin
2025-04-07 18:10 ` Sasha Levin [this message]
2025-04-08 4:29 ` [PATCH AUTOSEL 6.14 25/31] um: Switch to the pthread-based helper in sigio workaround Tiwei Bie
2025-04-07 18:10 ` [PATCH AUTOSEL 6.14 26/31] um: Rewrite the sigio workaround based on epoll and tgkill Sasha Levin
2025-04-08 4:36 ` Tiwei Bie
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20250407181054.3177479-25-sashal@kernel.org \
--to=sashal@kernel.org \
--cc=anton.ivanov@cambridgegreys.com \
--cc=johannes.berg@intel.com \
--cc=johannes@sipsolutions.net \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-um@lists.infradead.org \
--cc=richard@nod.at \
--cc=stable@vger.kernel.org \
--cc=tiwei.btw@antgroup.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).