Merge tag 'uml-for-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

Pull UML updates from Johannes Berg:
 "UML was _really_ quiet, with just four small commits:

   - two signal handling fixes

   - dynamic addition of virtio devices

   - a single code cleanup"

* tag 'uml-for-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux:
  arch/um: remove unused varible err in remove_files_and_dir()
  um: virtio_uml: Support adding devices via mconsole
  um: Handle SIGCHLD in seccomp mode like other IRQ signals
  um: Preserve errno within signal handler

Author: torvalds

arch/um/drivers/virtio_uml.c

@@ -34,6 +34,7 @@
 #include <irq_kern.h>
 #include <init.h>
 #include <os.h>
+#include "mconsole_kern.h"
 #include "vhost_user.h"
 
 #define MAX_SUPPORTED_QUEUE_SIZE	256
@@ -1282,6 +1283,7 @@ static struct device vu_cmdline_parent = {
 	.release = vu_cmdline_release_dev,
 };
 
+static DEFINE_MUTEX(vu_cmdline_lock);
 static bool vu_cmdline_parent_registered;
 static int vu_cmdline_id;
 
@@ -1309,7 +1311,7 @@ static void vu_conn_broken(struct work_struct *wk)
 	vu_unregister_cmdline_device(&pdata->pdev->dev, NULL);
 }
 
-static int vu_cmdline_set(const char *device, const struct kernel_param *kp)
+static int vu_cmdline_set_device(const char *device)
 {
 	const char *ids = strchr(device, ':');
 	unsigned int virtio_device_id;
@@ -1321,6 +1323,8 @@ static int vu_cmdline_set(const char *device, const struct kernel_param *kp)
 	if (!ids || ids == device)
 		return -EINVAL;
 
+	guard(mutex)(&vu_cmdline_lock);
+
 	processed = sscanf(ids, ":%u%n:%d%n",
 			   &virtio_device_id, &consumed,
 			   &vu_cmdline_id, &consumed);
@@ -1366,6 +1370,11 @@ static int vu_cmdline_set(const char *device, const struct kernel_param *kp)
 	return err;
 }
 
+static int vu_cmdline_set(const char *device, const struct kernel_param *kp)
+{
+	return vu_cmdline_set_device(device);
+}
+
 static int vu_cmdline_get_device(struct device *dev, void *data)
 {
 	struct platform_device *pdev = to_platform_device(dev);
@@ -1380,6 +1389,8 @@ static int vu_cmdline_get_device(struct device *dev, void *data)
 
 static int vu_cmdline_get(char *buffer, const struct kernel_param *kp)
 {
+	guard(mutex)(&vu_cmdline_lock);
+
 	buffer[0] = '\0';
 	if (vu_cmdline_parent_registered)
 		device_for_each_child(&vu_cmdline_parent, buffer,
@@ -1403,6 +1414,8 @@ __uml_help(vu_cmdline_param_ops,
 
 static void vu_unregister_cmdline_devices(void)
 {
+	guard(mutex)(&vu_cmdline_lock);
+
 	if (vu_cmdline_parent_registered) {
 		device_for_each_child(&vu_cmdline_parent, NULL,
 				      vu_unregister_cmdline_device);
@@ -1411,6 +1424,42 @@ static void vu_unregister_cmdline_devices(void)
 	}
 }
 
+static int vu_mc_config(char *str, char **error_out)
+{
+	if (*str != '=') {
+		*error_out = "Invalid config";
+		return -EINVAL;
+	}
+	str += 1;
+	return vu_cmdline_set_device(str);
+}
+
+static int vu_mc_id(char **str, int *start_out, int *end_out)
+{
+	return -EOPNOTSUPP;
+}
+
+static int vu_mc_remove(int n, char **error_out)
+{
+	return -EOPNOTSUPP;
+}
+
+static struct mc_device virtio_uml_mc = {
+	.list		= LIST_HEAD_INIT(virtio_uml_mc.list),
+	.name		= "virtio_uml.device",
+	.config		= vu_mc_config,
+	.get_config	= NULL,
+	.id		= vu_mc_id,
+	.remove		= vu_mc_remove,
+};
+
+static int __init virtio_uml_mc_init(void)
+{
+	mconsole_register_dev(&virtio_uml_mc);
+	return 0;
+}
+late_initcall(virtio_uml_mc_init);
+
 /* Platform driver */
 
 static const struct of_device_id virtio_uml_match[] = {

arch/um/os-Linux/signal.c

@@ -16,6 +16,7 @@
 #include <as-layout.h>
 #include <kern_util.h>
 #include <os.h>
+#include <skas.h>
 #include <sysdep/mcontext.h>
 #include <um_malloc.h>
 #include <sys/ucontext.h>
@@ -36,7 +37,6 @@ void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *, void *mc) =
 static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
 {
 	struct uml_pt_regs r;
-	int save_errno = errno;
 
 	r.is_user = 0;
 	if (sig == SIGSEGV) {
@@ -50,8 +50,6 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
 		unblock_signals_trace();
 
 	(*sig_info[sig])(sig, si, &r, mc);
-
-	errno = save_errno;
 }
 
 /*
@@ -207,8 +205,11 @@ static void hard_handler(int sig, siginfo_t *si, void *p)
 {
 	ucontext_t *uc = p;
 	mcontext_t *mc = &uc->uc_mcontext;
+	int save_errno = errno;
 
 	(*handlers[sig])(sig, (struct siginfo *)si, mc);
+
+	errno = save_errno;
 }
 
 void set_handler(int sig)
@@ -224,6 +225,8 @@ void set_handler(int sig)
 	sigaddset(&action.sa_mask, SIGIO);
 	sigaddset(&action.sa_mask, SIGWINCH);
 	sigaddset(&action.sa_mask, SIGALRM);
+	if (using_seccomp)
+		sigaddset(&action.sa_mask, SIGCHLD);
 
 	if (sig == SIGSEGV)
 		flags |= SA_NODEFER;

arch/um/os-Linux/umid.c

@@ -136,7 +136,7 @@ static int remove_files_and_dir(char *dir)
 static inline int is_umdir_used(char *dir)
 {
 	char pid[sizeof("nnnnnnnnn")], *end, *file;
-	int fd, p, n, err;
+	int fd, p, n;
 	size_t filelen = strlen(dir) + sizeof("/pid") + 1;
 
 	file = malloc(filelen);
@@ -155,7 +155,6 @@ static inline int is_umdir_used(char *dir)
 		goto out;
 	}
 
-	err = 0;
 	n = read(fd, pid, sizeof(pid));
 	if (n < 0) {
 		printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file "