From: Guillaume Chazarain kmsg_write returns with printk, so some programs may be confused by a successful write() with a return value different than the buffer length. # /bin/echo something > /dev/kmsg /bin/echo: write error: Inappropriate ioctl for device The drawbacks is that the printk return value can no more be quickly checked from userspace. Signed-off-by: Guillaume Chazarain Signed-off-by: Andrew Morton --- drivers/char/mem.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletion(-) diff -puN drivers/char/mem.c~kmsg_write-dont-return-printk-return-value drivers/char/mem.c --- 25/drivers/char/mem.c~kmsg_write-dont-return-printk-return-value Tue Nov 15 16:18:59 2005 +++ 25-akpm/drivers/char/mem.c Tue Nov 15 16:18:59 2005 @@ -817,7 +817,7 @@ static ssize_t kmsg_write(struct file * size_t count, loff_t *ppos) { char *tmp; - int ret; + ssize_t ret; tmp = kmalloc(count + 1, GFP_KERNEL); if (tmp == NULL) @@ -826,6 +826,9 @@ static ssize_t kmsg_write(struct file * if (!copy_from_user(tmp, buf, count)) { tmp[count] = 0; ret = printk("%s", tmp); + if (ret > count) + /* printk can add a prefix */ + ret = count; } kfree(tmp); return ret; _