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Commit db1dd4d3 authored by Jonathan Corbet's avatar Jonathan Corbet
Browse files

Use f_lock to protect f_flags 



Traditionally, changes to struct file->f_flags have been done under BKL
protection, or with no protection at all.  This patch causes all f_flags
changes after file open/creation time to be done under protection of
f_lock.  This allows the removal of some BKL usage and fixes a number of
longstanding (if microscopic) races.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent 68499914

drivers/char/tty_io.c

+2 −3
Original line number Original line Diff line number Diff line
@@ -2162,13 +2162,12 @@ static int fionbio(struct file *file, int __user *p) 
	if (get_user(nonblock, p))

	if (get_user(nonblock, p))

		return -EFAULT;

		return -EFAULT;





	/* file->f_flags is still BKL protected in the fs layer - vomit */

	spin_lock(&file->f_lock);

	lock_kernel();

	if (nonblock)

	if (nonblock)

		file->f_flags |= O_NONBLOCK;

		file->f_flags |= O_NONBLOCK;

	else

	else

		file->f_flags &= ~O_NONBLOCK;

		file->f_flags &= ~O_NONBLOCK;

	unlock_kernel();

	spin_unlock(&file->f_lock);

	return 0;

	return 0;

}

}

drivers/usb/gadget/file_storage.c

+6 −1
Original line number Original line Diff line number Diff line
@@ -1711,7 +1711,9 @@ static int do_write(struct fsg_dev *fsg) 
		curlun->sense_data = SS_WRITE_PROTECTED;

		curlun->sense_data = SS_WRITE_PROTECTED;

		return -EINVAL;

		return -EINVAL;

	}

	}

	spin_lock(&curlun->filp->f_lock);

	curlun->filp->f_flags &= ~O_SYNC;	// Default is not to wait

	curlun->filp->f_flags &= ~O_SYNC;	// Default is not to wait

	spin_unlock(&curlun->filp->f_lock);





	/* Get the starting Logical Block Address and check that it's

	/* Get the starting Logical Block Address and check that it's

	 * not too big */

	 * not too big */
@@ -1728,8 +1730,11 @@ static int do_write(struct fsg_dev *fsg) 
			curlun->sense_data = SS_INVALID_FIELD_IN_CDB;

			curlun->sense_data = SS_INVALID_FIELD_IN_CDB;

			return -EINVAL;

			return -EINVAL;

		}

		}

		if (fsg->cmnd[1] & 0x08)	// FUA

		if (fsg->cmnd[1] & 0x08) {	// FUA

			spin_lock(&curlun->filp->f_lock);

			curlun->filp->f_flags |= O_SYNC;

			curlun->filp->f_flags |= O_SYNC;

			spin_unlock(&curlun->filp->f_lock);

		}

	}

	}

	if (lba >= curlun->num_sectors) {

	if (lba >= curlun->num_sectors) {

		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;

		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;

fs/fcntl.c

+2 −0
Original line number Original line Diff line number Diff line
@@ -189,7 +189,9 @@ static int setfl(int fd, struct file * filp, unsigned long arg) 
		}

		}

	}

	}





	spin_lock(&filp->f_lock);

	filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);

	filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);

	spin_unlock(&filp->f_lock);

 out:

 out:

	unlock_kernel();

	unlock_kernel();

	return error;

	return error;

fs/ioctl.c

+4 −3
Original line number Original line Diff line number Diff line
@@ -404,10 +404,12 @@ static int ioctl_fionbio(struct file *filp, int __user *argp) 
	if (O_NONBLOCK != O_NDELAY)

	if (O_NONBLOCK != O_NDELAY)

		flag |= O_NDELAY;

		flag |= O_NDELAY;

#endif

#endif

	spin_lock(&filp->f_lock);

	if (on)

	if (on)

		filp->f_flags |= flag;

		filp->f_flags |= flag;

	else

	else

		filp->f_flags &= ~flag;

		filp->f_flags &= ~flag;

	spin_unlock(&filp->f_lock);

	return error;

	return error;

}

}
@@ -432,10 +434,12 @@ static int ioctl_fioasync(unsigned int fd, struct file *filp, 
	if (error)

	if (error)

		return error;

		return error;





	spin_lock(&filp->f_lock);

	if (on)

	if (on)

		filp->f_flags |= FASYNC;

		filp->f_flags |= FASYNC;

	else

	else

		filp->f_flags &= ~FASYNC;

		filp->f_flags &= ~FASYNC;

	spin_unlock(&filp->f_lock);

	return error;

	return error;

}

}
@@ -499,10 +503,7 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd, 
		break;

		break;





	case FIONBIO:

	case FIONBIO:

		/* BKL needed to avoid races tweaking f_flags */

		lock_kernel();

		error = ioctl_fionbio(filp, argp);

		error = ioctl_fionbio(filp, argp);

		unlock_kernel();

		break;

		break;





	case FIOASYNC:

	case FIOASYNC:

fs/nfsd/vfs.c

+4 −1
Original line number Original line Diff line number Diff line
@@ -998,8 +998,11 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file, 




	if (!EX_ISSYNC(exp))

	if (!EX_ISSYNC(exp))

		stable = 0;

		stable = 0;

	if (stable && !EX_WGATHER(exp))

	if (stable && !EX_WGATHER(exp)) {

		spin_lock(&file->f_lock);

		file->f_flags |= O_SYNC;

		file->f_flags |= O_SYNC;

		spin_unlock(&file->f_lock);

	}





	/* Write the data. */

	/* Write the data. */

	oldfs = get_fs(); set_fs(KERNEL_DS);

	oldfs = get_fs(); set_fs(KERNEL_DS);