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);