UML: Remove sigio_lock()/sigio_unlock() lockdep warnings
When lockdep is enabled on UML, calls to sigio_lock() and
sigio_unlock() trigger a lockdep warning since this function is called
both from interrupt context and process context. This patch allows a
"flags" argument to be passed to sigio_lock() and sigio_unlock() to
allow them to use spin_lock_irqsave() and spin_unlock_irqrestore().
Signed-off-by: Paul Menage <men...@google.com>
---
arch/um/include/shared/sigio.h | 4 +--
arch/um/kernel/sigio.c | 8 +++---
arch/um/os-Linux/sigio.c | 55 +++++++++++++++++++++-------------------
3 files changed, 35 insertions(+), 32 deletions(-)
diff --git a/arch/um/include/shared/sigio.h b/arch/um/include/shared/sigio.h
index 434f1a9..5b16047 100644
--- a/arch/um/include/shared/sigio.h
+++ b/arch/um/include/shared/sigio.h
@@ -8,7 +8,7 @@
extern int write_sigio_irq(int fd);
extern int register_sigio_fd(int fd);
-extern void sigio_lock(void);
-extern void sigio_unlock(void);
+extern void sigio_lock(unsigned long *flags);
+extern void sigio_unlock(unsigned long flags);
#endif
diff --git a/arch/um/kernel/sigio.c b/arch/um/kernel/sigio.c
index 2b272b6..f258501 100644
--- a/arch/um/kernel/sigio.c
+++ b/arch/um/kernel/sigio.c
@@ -39,12 +39,12 @@ int write_sigio_irq(int fd)
/* These are called from os-Linux/sigio.c to protect its pollfds arrays. */
static DEFINE_SPINLOCK(sigio_spinlock);
-void sigio_lock(void)
+void sigio_lock(unsigned long *flags)
{
- spin_lock(&sigio_spinlock);
+ spin_lock_irqsave(&sigio_spinlock, *flags);
}
-void sigio_unlock(void)
+void sigio_unlock(unsigned long flags)
{
- spin_unlock(&sigio_spinlock);
+ spin_unlock_irqrestore(&sigio_spinlock, flags);
}
diff --git a/arch/um/os-Linux/sigio.c b/arch/um/os-Linux/sigio.c
index 63d299d..aa85a5c 100644
--- a/arch/um/os-Linux/sigio.c
+++ b/arch/um/os-Linux/sigio.c
@@ -24,6 +24,8 @@
* Protected by sigio_lock(), also used by sigio_cleanup, which is an
* exitcall.
*/
+
+/* -1 => uninitialized, -2 => initializing */
static int write_sigio_pid = -1;
static unsigned long write_sigio_stack;
@@ -171,8 +173,9 @@ int add_sigio_fd(int fd)
{
struct pollfd *p;
int err = 0, i, n;
+ unsigned long flags;
- sigio_lock();
+ sigio_lock(&flags);
for (i = 0; i < all_sigio_fds.used; i++) {
if (all_sigio_fds.poll[i].fd == fd)
break;
@@ -198,7 +201,7 @@ int add_sigio_fd(int fd)
next_poll.used = n + 1;
update_thread();
out:
- sigio_unlock();
+ sigio_unlock(flags);
return err;
}
@@ -206,6 +209,7 @@ int ignore_sigio_fd(int fd)
{
struct pollfd *p;
int err = 0, i, n = 0;
+ unsigned long flags;
/*
* This is called from exitcalls elsewhere in UML - if
@@ -215,7 +219,7 @@ int ignore_sigio_fd(int fd)
if (write_sigio_pid == -1)
return -EIO;
- sigio_lock();
+ sigio_lock(&flags);
for (i = 0; i < current_poll.used; i++) {
if (current_poll.poll[i].fd == fd)
break;
@@ -236,7 +240,7 @@ int ignore_sigio_fd(int fd)
update_thread();
out:
- sigio_unlock();
+ sigio_unlock(flags);
return err;
}
@@ -262,15 +266,20 @@ static void write_sigio_workaround(void)
int err;
int l_write_sigio_fds[2];
int l_sigio_private[2];
- int l_write_sigio_pid;
+ unsigned long flags;
/* We call this *tons* of times - and most ones we must just fail. */
- sigio_lock();
- l_write_sigio_pid = write_sigio_pid;
- sigio_unlock();
-
- if (l_write_sigio_pid != -1)
+ again:
+ sigio_lock(&flags);
+ if (write_sigio_pid >= 0) {
+ sigio_unlock(flags);
return;
+ } else if (write_sigio_pid == -2) {
+ sigio_unlock(flags);
+ goto again;
+ }
+ write_sigio_pid = -2;
+ sigio_unlock(flags);
err = os_pipe(l_write_sigio_fds, 1, 1);
if (err < 0) {
@@ -289,22 +298,16 @@ static void write_sigio_workaround(void)
if (!p)
goto out_close2;
- 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_free;
+ if (write_sigio_irq(l_write_sigio_fds[0])) {
+ sigio_lock(&flags);
+ goto out_clear_poll;
+ }
+ sigio_lock(&flags);
current_poll = ((struct pollfds) { .poll = p,
.used = 1,
.size = 1 });
- if (write_sigio_irq(l_write_sigio_fds[0]))
- goto out_clear_poll;
-
memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
@@ -315,7 +318,7 @@ static void write_sigio_workaround(void)
if (write_sigio_pid < 0)
goto out_clear;
- sigio_unlock();
+ sigio_unlock(flags);
return;
out_clear:
@@ -328,9 +331,8 @@ out_clear_poll:
current_poll = ((struct pollfds) { .poll = NULL,
.size = 0,
.used = 0 });
-out_free:
- sigio_unlock();
kfree(p);
+ sigio_unlock(flags);
out_close2:
close(l_sigio_private[0]);
close(l_sigio_private[1]);
@@ -342,10 +344,11 @@ out_close1:
void sigio_broken(int fd, int read)
{
int err;
+ unsigned long flags;
write_sigio_workaround();
- sigio_lock();
+ sigio_lock(&flags);
err = need_poll(&all_sigio_fds, all_sigio_fds.used + 1);
if (err) {
printk(UM_KERN_ERR "maybe_sigio_broken - failed to add pollfd "
@@ -358,7 +361,7 @@ void sigio_broken(int fd, int read)
.events = read ? POLLIN : POLLOUT,
.revents = 0 });
out:
- sigio_unlock();
+ sigio_unlock(flags);
}
/* Changed during early boot */
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