diff options
Diffstat (limited to 'drivers/mtd/mtdchar.c')
| -rw-r--r-- | drivers/mtd/mtdchar.c | 55 |
1 files changed, 23 insertions, 32 deletions
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c index 4c36ef66a46..3f92731a5b9 100644 --- a/drivers/mtd/mtdchar.c +++ b/drivers/mtd/mtdchar.c @@ -166,10 +166,23 @@ static int mtd_close(struct inode *inode, struct file *file) return 0; } /* mtd_close */ -/* FIXME: This _really_ needs to die. In 2.5, we should lock the - userspace buffer down and use it directly with readv/writev. -*/ -#define MAX_KMALLOC_SIZE 0x20000 +/* Back in June 2001, dwmw2 wrote: + * + * FIXME: This _really_ needs to die. In 2.5, we should lock the + * userspace buffer down and use it directly with readv/writev. + * + * The implementation below, using mtd_kmalloc_up_to, mitigates + * allocation failures when the system is under low-memory situations + * or if memory is highly fragmented at the cost of reducing the + * performance of the requested transfer due to a smaller buffer size. + * + * A more complex but more memory-efficient implementation based on + * get_user_pages and iovecs to cover extents of those pages is a + * longer-term goal, as intimated by dwmw2 above. However, for the + * write case, this requires yet more complex head and tail transfer + * handling when those head and tail offsets and sizes are such that + * alignment requirements are not met in the NAND subdriver. + */ static ssize_t mtd_read(struct file *file, char __user *buf, size_t count,loff_t *ppos) { @@ -179,6 +192,7 @@ static ssize_t mtd_read(struct file *file, char __user *buf, size_t count,loff_t size_t total_retlen=0; int ret=0; int len; + size_t size = count; char *kbuf; DEBUG(MTD_DEBUG_LEVEL0,"MTD_read\n"); @@ -189,23 +203,12 @@ static ssize_t mtd_read(struct file *file, char __user *buf, size_t count,loff_t if (!count) return 0; - /* FIXME: Use kiovec in 2.5 to lock down the user's buffers - and pass them directly to the MTD functions */ - - if (count > MAX_KMALLOC_SIZE) - kbuf=kmalloc(MAX_KMALLOC_SIZE, GFP_KERNEL); - else - kbuf=kmalloc(count, GFP_KERNEL); - + kbuf = mtd_kmalloc_up_to(mtd, &size); if (!kbuf) return -ENOMEM; while (count) { - - if (count > MAX_KMALLOC_SIZE) - len = MAX_KMALLOC_SIZE; - else - len = count; + len = min_t(size_t, count, size); switch (mfi->mode) { case MTD_MODE_OTP_FACTORY: @@ -268,6 +271,7 @@ static ssize_t mtd_write(struct file *file, const char __user *buf, size_t count { struct mtd_file_info *mfi = file->private_data; struct mtd_info *mtd = mfi->mtd; + size_t size = count; char *kbuf; size_t retlen; size_t total_retlen=0; @@ -285,20 +289,12 @@ static ssize_t mtd_write(struct file *file, const char __user *buf, size_t count if (!count) return 0; - if (count > MAX_KMALLOC_SIZE) - kbuf=kmalloc(MAX_KMALLOC_SIZE, GFP_KERNEL); - else - kbuf=kmalloc(count, GFP_KERNEL); - + kbuf = mtd_kmalloc_up_to(mtd, &size); if (!kbuf) return -ENOMEM; while (count) { - - if (count > MAX_KMALLOC_SIZE) - len = MAX_KMALLOC_SIZE; - else - len = count; + len = min_t(size_t, count, size); if (copy_from_user(kbuf, buf, len)) { kfree(kbuf); @@ -512,7 +508,6 @@ static int shrink_ecclayout(const struct nand_ecclayout *from, return 0; } -#ifdef CONFIG_MTD_PARTITIONS static int mtd_blkpg_ioctl(struct mtd_info *mtd, struct blkpg_ioctl_arg __user *arg) { @@ -548,8 +543,6 @@ static int mtd_blkpg_ioctl(struct mtd_info *mtd, return -EINVAL; } } -#endif - static int mtd_ioctl(struct file *file, u_int cmd, u_long arg) { @@ -941,7 +934,6 @@ static int mtd_ioctl(struct file *file, u_int cmd, u_long arg) break; } -#ifdef CONFIG_MTD_PARTITIONS case BLKPG: { ret = mtd_blkpg_ioctl(mtd, @@ -955,7 +947,6 @@ static int mtd_ioctl(struct file *file, u_int cmd, u_long arg) ret = 0; break; } -#endif default: ret = -ENOTTY; |