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Diffstat (limited to 'arch')
-rw-r--r--arch/um/kernel/sigio_user.c83
1 files changed, 58 insertions, 25 deletions
diff --git a/arch/um/kernel/sigio_user.c b/arch/um/kernel/sigio_user.c
index 62e5cfdf2188..f7b18e157d35 100644
--- a/arch/um/kernel/sigio_user.c
+++ b/arch/um/kernel/sigio_user.c
@@ -337,70 +337,103 @@ int ignore_sigio_fd(int fd)
return(err);
}
-static int setup_initial_poll(int fd)
+static struct pollfd* setup_initial_poll(int fd)
{
struct pollfd *p;
- p = um_kmalloc_atomic(sizeof(struct pollfd));
- if(p == NULL){
+ p = um_kmalloc(sizeof(struct pollfd));
+ if (p == NULL) {
printk("setup_initial_poll : failed to allocate poll\n");
- return(-1);
+ return NULL;
}
*p = ((struct pollfd) { .fd = fd,
.events = POLLIN,
.revents = 0 });
- current_poll = ((struct pollfds) { .poll = p,
- .used = 1,
- .size = 1 });
- return(0);
+ return p;
}
void write_sigio_workaround(void)
{
unsigned long stack;
+ struct pollfd *p;
int err;
+ int l_write_sigio_fds[2];
+ int l_sigio_private[2];
+ int l_write_sigio_pid;
+ /* We call this *tons* of times - and most ones we must just fail. */
sigio_lock();
- if(write_sigio_pid != -1)
- goto out;
+ l_write_sigio_pid = write_sigio_pid;
+ sigio_unlock();
- err = os_pipe(write_sigio_fds, 1, 1);
+ if (l_write_sigio_pid != -1)
+ return;
+
+ err = os_pipe(l_write_sigio_fds, 1, 1);
if(err < 0){
printk("write_sigio_workaround - os_pipe 1 failed, "
"err = %d\n", -err);
- goto out;
+ return;
}
- err = os_pipe(sigio_private, 1, 1);
+ err = os_pipe(l_sigio_private, 1, 1);
if(err < 0){
- printk("write_sigio_workaround - os_pipe 2 failed, "
+ printk("write_sigio_workaround - os_pipe 1 failed, "
"err = %d\n", -err);
goto out_close1;
}
- if(setup_initial_poll(sigio_private[1]))
+
+ p = setup_initial_poll(l_sigio_private[1]);
+ if(!p)
goto out_close2;
- write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
+ sigio_lock();
+
+ /* 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)
+ goto out_unlock;
+
+ write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
CLONE_FILES | CLONE_VM, &stack, 0);
- if(write_sigio_pid < 0) goto out_close2;
+ if (write_sigio_pid < 0)
+ goto out_clear;
- if(write_sigio_irq(write_sigio_fds[0]))
+ if (write_sigio_irq(l_write_sigio_fds[0]))
goto out_kill;
- out:
+ /* Success, finally. */
+ memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
+ memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
+
+ current_poll = ((struct pollfds) { .poll = p,
+ .used = 1,
+ .size = 1 });
+
sigio_unlock();
return;
out_kill:
- os_kill_process(write_sigio_pid, 1);
+ l_write_sigio_pid = write_sigio_pid;
write_sigio_pid = -1;
+ sigio_unlock();
+ /* Going to call waitpid, avoid holding the lock. */
+ os_kill_process(l_write_sigio_pid, 1);
+ goto out_free;
+
+ out_clear:
+ write_sigio_pid = -1;
+ out_unlock:
+ sigio_unlock();
+ out_free:
+ kfree(p);
out_close2:
- os_close_file(sigio_private[0]);
- os_close_file(sigio_private[1]);
+ os_close_file(l_sigio_private[0]);
+ os_close_file(l_sigio_private[1]);
out_close1:
- os_close_file(write_sigio_fds[0]);
- os_close_file(write_sigio_fds[1]);
- sigio_unlock();
+ os_close_file(l_write_sigio_fds[0]);
+ os_close_file(l_write_sigio_fds[1]);
+ return;
}
int read_sigio_fd(int fd)