[MTD] mtdoops: Perform write operations in a workqueue

Writing to the flash needs to be done in a workqueue. The console
write functions may be called in any context which can lead to
lockups otherwise.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

1 files changed, 42 insertions, 40 deletions

diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index 723ca76d6b55..72c434c61b0a 100644
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -32,9 +32,10 @@
 
 #define OOPS_PAGE_SIZE 4096
 
-static struct mtdoops_context {
+struct mtdoops_context {
         int mtd_index;
-        struct work_struct work;
+        struct work_struct work_erase;
+        struct work_struct work_write;
         struct mtd_info *mtd;
         int oops_pages;
         int nextpage;
@@ -87,7 +88,7 @@ static int mtdoops_erase_block(struct mtd_info *mtd, int offset)
         return 0;
 }
 
-static int mtdoops_inc_counter(struct mtdoops_context *cxt)
+static void mtdoops_inc_counter(struct mtdoops_context *cxt)
 {
         struct mtd_info *mtd = cxt->mtd;
         size_t retlen;
@@ -107,21 +108,26 @@ static int mtdoops_inc_counter(struct mtdoops_context *cxt)
                 printk(KERN_ERR "mtdoops: Read failure at %d (%td of 4 read)"
                                 ", err %d.\n", cxt->nextpage * OOPS_PAGE_SIZE,
                                 retlen, ret);
-                return 1;
+                schedule_work(&cxt->work_erase);
+                return;
         }
 
         /* See if we need to erase the next block */
-        if (count != 0xffffffff)
-                return 1;
+        if (count != 0xffffffff) {
+                schedule_work(&cxt->work_erase);
+                return;
+        }
 
         printk(KERN_DEBUG "mtdoops: Ready %d, %d (no erase)\n",
                         cxt->nextpage, cxt->nextcount);
         cxt->ready = 1;
-        return 0;
 }
 
-static void mtdoops_prepare(struct mtdoops_context *cxt)
+/* Scheduled work - when we can't proceed without erasing a block */
+static void mtdoops_workfunc_erase(struct work_struct *work)
 {
+        struct mtdoops_context *cxt =
+                        container_of(work, struct mtdoops_context, work_erase);
         struct mtd_info *mtd = cxt->mtd;
         int i = 0, j, ret, mod;
 
@@ -176,15 +182,31 @@ badblock:
         goto badblock;
 }
 
-static void mtdoops_workfunc(struct work_struct *work)
+static void mtdoops_workfunc_write(struct work_struct *work)
 {
         struct mtdoops_context *cxt =
-                        container_of(work, struct mtdoops_context, work);
+                        container_of(work, struct mtdoops_context, work_write);
+        struct mtd_info *mtd = cxt->mtd;
+        size_t retlen;
+        int ret;
 
-        mtdoops_prepare(cxt);
-}
+        if (cxt->writecount < OOPS_PAGE_SIZE)
+                memset(cxt->oops_buf + cxt->writecount, 0xff,
+                                        OOPS_PAGE_SIZE - cxt->writecount);
+
+        ret = mtd->write(mtd, cxt->nextpage * OOPS_PAGE_SIZE,
+                                        OOPS_PAGE_SIZE, &retlen, cxt->oops_buf);
+
+        cxt->writecount = 0;
+
+        if ((retlen != OOPS_PAGE_SIZE) || (ret < 0))
+                printk(KERN_ERR "mtdoops: Write failure at %d (%td of %d written), err %d.\n",
+                        cxt->nextpage * OOPS_PAGE_SIZE, retlen, OOPS_PAGE_SIZE, ret);
+
+        mtdoops_inc_counter(cxt);
+}                                       
 
-static int find_next_position(struct mtdoops_context *cxt)
+static void find_next_position(struct mtdoops_context *cxt)
 {
         struct mtd_info *mtd = cxt->mtd;
         int ret, page, maxpos = 0;
@@ -222,20 +244,19 @@ static int find_next_position(struct mtdoops_context *cxt)
                 cxt->ready = 1;
                 printk(KERN_DEBUG "mtdoops: Ready %d, %d (first init)\n",
                                 cxt->nextpage, cxt->nextcount);
-                return 0;
+                return;
         }
 
         cxt->nextpage = maxpos;
         cxt->nextcount = maxcount;
 
-        return mtdoops_inc_counter(cxt);
+        mtdoops_inc_counter(cxt);
 }
 
 
 static void mtdoops_notify_add(struct mtd_info *mtd)
 {
         struct mtdoops_context *cxt = &oops_cxt;
-        int ret;
 
         if ((mtd->index != cxt->mtd_index) || cxt->mtd_index < 0)
                 return;
@@ -249,9 +270,7 @@ static void mtdoops_notify_add(struct mtd_info *mtd)
         cxt->mtd = mtd;
         cxt->oops_pages = mtd->size / OOPS_PAGE_SIZE;
 
-        ret = find_next_position(cxt);
-        if (ret == 1)
-                mtdoops_prepare(cxt);
+        find_next_position(cxt);
 
         printk(KERN_DEBUG "mtdoops: Attached to MTD device %d\n", mtd->index);
 }
@@ -271,31 +290,13 @@ static void mtdoops_console_sync(void)
 {
         struct mtdoops_context *cxt = &oops_cxt;
         struct mtd_info *mtd = cxt->mtd;
-        size_t retlen;
-        int ret;
 
-        if (!cxt->ready || !mtd)
+        if (!cxt->ready || !mtd || cxt->writecount == 0)
                 return;
 
-        if (cxt->writecount == 0)
-                return;
-
-        if (cxt->writecount < OOPS_PAGE_SIZE)
-                memset(cxt->oops_buf + cxt->writecount, 0xff,
-                                        OOPS_PAGE_SIZE - cxt->writecount);
-
-        ret = mtd->write(mtd, cxt->nextpage * OOPS_PAGE_SIZE,
-                                        OOPS_PAGE_SIZE, &retlen, cxt->oops_buf);
         cxt->ready = 0;
-        cxt->writecount = 0;
-
-        if ((retlen != OOPS_PAGE_SIZE) || (ret < 0))
-                printk(KERN_ERR "mtdoops: Write failure at %d (%td of %d written), err %d.\n",
-                        cxt->nextpage * OOPS_PAGE_SIZE, retlen, OOPS_PAGE_SIZE, ret);
 
-        ret = mtdoops_inc_counter(cxt);
-        if (ret == 1)
-                schedule_work(&cxt->work);
+        schedule_work(&cxt->work_write);
 }
 
 static void
@@ -365,7 +366,8 @@ static int __init mtdoops_console_init(void)
                 return -ENOMEM;
         }
 
-        INIT_WORK(&cxt->work, mtdoops_workfunc);
+        INIT_WORK(&cxt->work_erase, mtdoops_workfunc_erase);
+        INIT_WORK(&cxt->work_write, mtdoops_workfunc_write);
 
         register_console(&mtdoops_console);
         register_mtd_user(&mtdoops_notifier);