On Thu, May 03, 2007 at 11:14:50PM -0700, Andrew Morton wrote: >On Sat, 28 Apr 2007 13:30:23 +0800 WANG Cong <[EMAIL PROTECTED]> wrote: > >> Since 'sysfs_create_file' is declared with attribute warn_unused_result, we >> must always check its return value carefully. >> > >Well that's not really the reason for your patch. > >warn_unused_result is there to tell us that there are deeper problems in >the code which need addressing: the failure to check the >sysfs_create_file() return value means that bugs in the kernel can remain >undetected, or can be harder to find.
Oh, thanks very much for your pointing. > >> >> --- >> >> --- linux-2.6.21-rc7-mm2/drivers/block/nbd.c.orig 2007-04-27 >> 17:27:47.000000000 +0800 >> +++ linux-2.6.21-rc7-mm2/drivers/block/nbd.c 2007-04-27 17:47:32.000000000 >> +0800 >> @@ -373,7 +373,10 @@ static void nbd_do_it(struct nbd_device >> BUG_ON(lo->magic != LO_MAGIC); >> >> lo->pid = current->pid; >> - sysfs_create_file(&lo->disk->kobj, &pid_attr.attr); >> + if (sysfs_create_file(&lo->disk->kobj, &pid_attr.attr)) { >> + printk(KERN_ERR "nbd: sysfs_create_file failed!"); >> + return; >> + } >> >> while ((req = nbd_read_stat(lo)) != NULL) >> nbd_end_request(req); > >It would better saner to propagate this error back through callers: > >--- a/drivers/block/nbd.c~nbd-check-the-return-value-of-sysfs_create_file-fix >+++ a/drivers/block/nbd.c >@@ -366,23 +366,25 @@ static struct disk_attribute pid_attr = > .show = pid_show, > }; > >-static void nbd_do_it(struct nbd_device *lo) >+static int nbd_do_it(struct nbd_device *lo) > { > struct request *req; >+ int ret; > > BUG_ON(lo->magic != LO_MAGIC); > > lo->pid = current->pid; >- if (sysfs_create_file(&lo->disk->kobj, &pid_attr.attr)) { >+ ret = sysfs_create_file(&lo->disk->kobj, &pid_attr.attr); >+ if (ret) { > printk(KERN_ERR "nbd: sysfs_create_file failed!"); >- return; >+ return ret; > } > > while ((req = nbd_read_stat(lo)) != NULL) > nbd_end_request(req); > > sysfs_remove_file(&lo->disk->kobj, &pid_attr.attr); >- return; >+ return 0; > } > > static void nbd_clear_que(struct nbd_device *lo) >@@ -572,7 +574,9 @@ static int nbd_ioctl(struct inode *inode > case NBD_DO_IT: > if (!lo->file) > return -EINVAL; >- nbd_do_it(lo); >+ error = nbd_do_it(lo); >+ if (error) >+ return error; > /* on return tidy up in case we have a signal */ > /* Forcibly shutdown the socket causing all listeners > * to error >_ Well, better code. ;) I didn't consider changing the type of nbd_do_it(). Thanks again! - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/