[PATCH v2 2/2] generic: platform/mikrotik: use MTD notifier

Denis Kalashnikov denis281089 at gmail.com
Tue Nov 16 08:06:44 PST 2021


If the SPI probe is sufficiently delayed, the routerboot driver may fail
to init as the routerboot partitions are not yet available.

Register an MTD user notifier instead of doing straight init so that the
init subroutines are only executed when the target MTD partitions are
present.

Because the init/exit routines can now be called outside of the kernel
normal init/exit calls, they cannot be jettisoned and must always be
available: the __init and __exit qualifiers are thus removed.

Reported-by: Denis Kalashnikov <denis281089 at gmail.com>
Signed-off-by: Denis Kalashnikov <denis281089 at gmail.com>
Signed-off-by: Thibaut VARÈNE <hacks at slashdirt.org>
---

v2:
* Use MTD notifier (hopefully a robust and right way of doing this thing)
  instead of late_initcall workaround.

v1:
* Replace module_init() with late_intcall() in routerboot module.

 .../drivers/platform/mikrotik/rb_hardconfig.c | 16 +++----
 .../drivers/platform/mikrotik/rb_softconfig.c | 16 +++----
 .../drivers/platform/mikrotik/routerboot.c    | 45 ++++++++++++++++---
 .../drivers/platform/mikrotik/routerboot.h    |  8 ++--
 4 files changed, 59 insertions(+), 26 deletions(-)

diff --git a/target/linux/generic/files/drivers/platform/mikrotik/rb_hardconfig.c b/target/linux/generic/files/drivers/platform/mikrotik/rb_hardconfig.c
index e6a6928896..5ba8b376f2 100644
--- a/target/linux/generic/files/drivers/platform/mikrotik/rb_hardconfig.c
+++ b/target/linux/generic/files/drivers/platform/mikrotik/rb_hardconfig.c
@@ -676,10 +676,9 @@ static ssize_t hc_wlan_data_bin_read(struct file *filp, struct kobject *kobj,
 	return count;
 }
 
-int __init rb_hardconfig_init(struct kobject *rb_kobj)
+int rb_hardconfig_init(struct kobject *rb_kobj, struct mtd_info *mtd)
 {
 	struct kobject *hc_wlan_kobj;
-	struct mtd_info *mtd;
 	size_t bytes_read, buflen, outlen;
 	const u8 *buf;
 	void *outbuf;
@@ -690,20 +689,19 @@ int __init rb_hardconfig_init(struct kobject *rb_kobj)
 	hc_kobj = NULL;
 	hc_wlan_kobj = NULL;
 
-	// TODO allow override
-	mtd = get_mtd_device_nm(RB_MTD_HARD_CONFIG);
-	if (IS_ERR(mtd))
+	ret = __get_mtd_device(mtd);
+	if (ret)
 		return -ENODEV;
 
 	hc_buflen = mtd->size;
 	hc_buf = kmalloc(hc_buflen, GFP_KERNEL);
 	if (!hc_buf) {
-		put_mtd_device(mtd);
+		__put_mtd_device(mtd);
 		return -ENOMEM;
 	}
 
 	ret = mtd_read(mtd, 0, hc_buflen, &bytes_read, hc_buf);
-	put_mtd_device(mtd);
+	__put_mtd_device(mtd);
 
 	if (ret)
 		goto fail;
@@ -818,8 +816,10 @@ fail:
 	return ret;
 }
 
-void __exit rb_hardconfig_exit(void)
+void rb_hardconfig_exit(void)
 {
 	kobject_put(hc_kobj);
+	hc_kobj = NULL;
 	kfree(hc_buf);
+	hc_buf = NULL;
 }
diff --git a/target/linux/generic/files/drivers/platform/mikrotik/rb_softconfig.c b/target/linux/generic/files/drivers/platform/mikrotik/rb_softconfig.c
index 070bd32d5a..5273b8d7ed 100644
--- a/target/linux/generic/files/drivers/platform/mikrotik/rb_softconfig.c
+++ b/target/linux/generic/files/drivers/platform/mikrotik/rb_softconfig.c
@@ -705,9 +705,8 @@ mtdfail:
 
 static struct kobj_attribute sc_kattrcommit = __ATTR(commit, RB_SC_RMODE|RB_SC_WMODE, sc_commit_show, sc_commit_store);
 
-int __init rb_softconfig_init(struct kobject *rb_kobj)
+int rb_softconfig_init(struct kobject *rb_kobj, struct mtd_info *mtd)
 {
-	struct mtd_info *mtd;
 	size_t bytes_read, buflen;
 	const u8 *buf;
 	int i, ret;
@@ -716,20 +715,19 @@ int __init rb_softconfig_init(struct kobject *rb_kobj)
 	sc_buf = NULL;
 	sc_kobj = NULL;
 
-	// TODO allow override
-	mtd = get_mtd_device_nm(RB_MTD_SOFT_CONFIG);
-	if (IS_ERR(mtd))
+	ret = __get_mtd_device(mtd);
+	if (ret)
 		return -ENODEV;
 
 	sc_buflen = mtd->size;
 	sc_buf = kmalloc(sc_buflen, GFP_KERNEL);
 	if (!sc_buf) {
-		put_mtd_device(mtd);
+		__put_mtd_device(mtd);
 		return -ENOMEM;
 	}
 
 	ret = mtd_read(mtd, 0, sc_buflen, &bytes_read, sc_buf);
-	put_mtd_device(mtd);
+	__put_mtd_device(mtd);
 
 	if (ret)
 		goto fail;
@@ -799,8 +797,10 @@ fail:
 	return ret;
 }
 
-void __exit rb_softconfig_exit(void)
+void rb_softconfig_exit(void)
 {
 	kobject_put(sc_kobj);
+	sc_kobj = NULL;
 	kfree(sc_buf);
+	sc_buf = NULL;
 }
diff --git a/target/linux/generic/files/drivers/platform/mikrotik/routerboot.c b/target/linux/generic/files/drivers/platform/mikrotik/routerboot.c
index 4c8c0bfac5..96f2460916 100644
--- a/target/linux/generic/files/drivers/platform/mikrotik/routerboot.c
+++ b/target/linux/generic/files/drivers/platform/mikrotik/routerboot.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/sysfs.h>
+#include <linux/mtd/mtd.h>
 
 #include "routerboot.h"
 
@@ -160,25 +161,57 @@ fail:
 	return ret;
 }
 
-static int __init routerboot_init(void)
+static void routerboot_mtd_notifier_add(struct mtd_info *mtd)
 {
-	rb_kobj = kobject_create_and_add("mikrotik", firmware_kobj);
-	if (!rb_kobj)
-		return -ENOMEM;
+	/* Currently routerboot is only known to live on NOR flash */
+	if (mtd->type != MTD_NORFLASH)
+		return;
 
 	/*
 	 * We ignore the following return values and always register.
 	 * These init() routines are designed so that their failed state is
 	 * always manageable by the corresponding exit() calls.
+	 * Notifier is called with MTD mutex held: use __get/__put variants.
+	 * TODO: allow partition names override
 	 */
-	rb_hardconfig_init(rb_kobj);
-	rb_softconfig_init(rb_kobj);
+	if (!strcmp(mtd->name, RB_MTD_HARD_CONFIG))
+		rb_hardconfig_init(rb_kobj, mtd);
+	else if (!strcmp(mtd->name, RB_MTD_SOFT_CONFIG))
+		rb_softconfig_init(rb_kobj, mtd);
+}
+
+static void routerboot_mtd_notifier_remove(struct mtd_info *mtd)
+{
+	if (mtd->type != MTD_NORFLASH)
+		return;
+
+	if (!strcmp(mtd->name, RB_MTD_HARD_CONFIG))
+		rb_hardconfig_exit();
+	else if (!strcmp(mtd->name, RB_MTD_SOFT_CONFIG))
+		rb_softconfig_exit();
+}
+
+/* Note: using a notifier prevents qualifying init()/exit() functions with __init/__exit */
+static struct mtd_notifier routerboot_mtd_notifier = {
+	.add = routerboot_mtd_notifier_add,
+	.remove = routerboot_mtd_notifier_remove,
+};
+
+static int __init routerboot_init(void)
+{
+	rb_kobj = kobject_create_and_add("mikrotik", firmware_kobj);
+	if (!rb_kobj)
+		return -ENOMEM;
+
+	register_mtd_user(&routerboot_mtd_notifier);
 
 	return 0;
 }
 
 static void __exit routerboot_exit(void)
 {
+	unregister_mtd_user(&routerboot_mtd_notifier);
+	/* Exit routines are idempotent */
 	rb_softconfig_exit();
 	rb_hardconfig_exit();
 	kobject_put(rb_kobj);	// recursive afaict
diff --git a/target/linux/generic/files/drivers/platform/mikrotik/routerboot.h b/target/linux/generic/files/drivers/platform/mikrotik/routerboot.h
index 67d89808d5..e858a524af 100644
--- a/target/linux/generic/files/drivers/platform/mikrotik/routerboot.h
+++ b/target/linux/generic/files/drivers/platform/mikrotik/routerboot.h
@@ -25,11 +25,11 @@
 int routerboot_tag_find(const u8 *bufhead, const size_t buflen, const u16 tag_id, u16 *pld_ofs, u16 *pld_len);
 int routerboot_rle_decode(const u8 *in, size_t inlen, u8 *out, size_t *outlen);
 
-int __init rb_hardconfig_init(struct kobject *rb_kobj);
-void __exit rb_hardconfig_exit(void);
+int rb_hardconfig_init(struct kobject *rb_kobj, struct mtd_info *mtd);
+void rb_hardconfig_exit(void);
 
-int __init rb_softconfig_init(struct kobject *rb_kobj);
-void __exit rb_softconfig_exit(void);
+int rb_softconfig_init(struct kobject *rb_kobj, struct mtd_info *mtd);
+void rb_softconfig_exit(void);
 
 ssize_t routerboot_tag_show_string(const u8 *pld, u16 pld_len, char *buf);
 ssize_t routerboot_tag_show_u32s(const u8 *pld, u16 pld_len, char *buf);
-- 
2.31.1




More information about the openwrt-devel mailing list