[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>

diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index 723ca76..72c434c 100644 (file)
--- 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);