From: Geert Uytterhoeven <geert@linux-m68k.org> To: Dan Williams <dan.j.williams@intel.com> Cc: Jens Axboe <axboe@fb.com>, Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>, "linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>, Dave Chinner <david@fromorbit.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Jeff Moyer <jmoyer@redhat.com>, Jan Kara <jack@suse.com>, Ross Zwisler <ross.zwisler@linux.intel.com>, Christoph Hellwig <hch@lst.de> Subject: Re: [PATCH v3 03/15] block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic() Date: Mon, 18 Jan 2016 11:42:43 +0100 [thread overview] Message-ID: <CAMuHMdVTXDJ_KF95u+uNCJcs6pT2eJmVSg6at_vfAfp2ovctnQ@mail.gmail.com> (raw) In-Reply-To: <20151102042958.6610.65193.stgit@dwillia2-desk3.amr.corp.intel.com> Hi Dan, On Mon, Nov 2, 2015 at 5:29 AM, Dan Williams <dan.j.williams@intel.com> wrote: > The DAX implementation needs to protect new calls to ->direct_access() > and usage of its return value against unbind of the underlying block > device. Use blk_queue_enter()/blk_queue_exit() to either prevent > blk_cleanup_queue() from proceeding, or fail the dax_map_atomic() if the > request_queue is being torn down. > index f8e543839e5c..a480729c00ec 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, > loff_t start, loff_t end, get_block_t get_block, > struct buffer_head *bh) > { > - ssize_t retval = 0; > - loff_t pos = start; > - loff_t max = start; > - loff_t bh_max = start; > - void __pmem *addr; > + loff_t pos = start, max = start, bh_max = start; > + struct block_device *bdev = NULL; > + int rw = iov_iter_rw(iter), rc; fs/dax.c:138: warning: ‘rc’ may be used uninitialized in this function rc will be uninitialized if start == end, and the while loop below is never executed. I don't know whether it's 100% guaranteed this isn't the case. Note that the old retval was preinitialized to 0. > + long map_len = 0; > + unsigned long pfn; > + void __pmem *addr = NULL; > + void __pmem *kmap = (void __pmem *) ERR_PTR(-EIO); > bool hole = false; > bool need_wmb = false; > > - if (iov_iter_rw(iter) != WRITE) > + if (rw == READ) > end = min(end, i_size_read(inode)); > > while (pos < end) { > @@ -175,8 +219,9 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, > > if (need_wmb) > wmb_pmem(); > + dax_unmap_atomic(bdev, kmap); > > - return (pos == start) ? retval : pos - start; > + return (pos == start) ? rc : pos - start; > } Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
WARNING: multiple messages have this Message-ID (diff)
From: Geert Uytterhoeven <geert@linux-m68k.org> To: Dan Williams <dan.j.williams@intel.com> Cc: Jens Axboe <axboe@fb.com>, Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>, "linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>, Dave Chinner <david@fromorbit.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Jeff Moyer <jmoyer@redhat.com>, Jan Kara <jack@suse.com>, Ross Zwisler <ross.zwisler@linux.intel.com>, Christoph Hellwig <hch@lst.de> Subject: Re: [PATCH v3 03/15] block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic() Date: Mon, 18 Jan 2016 11:42:43 +0100 [thread overview] Message-ID: <CAMuHMdVTXDJ_KF95u+uNCJcs6pT2eJmVSg6at_vfAfp2ovctnQ@mail.gmail.com> (raw) In-Reply-To: <20151102042958.6610.65193.stgit@dwillia2-desk3.amr.corp.intel.com> Hi Dan, On Mon, Nov 2, 2015 at 5:29 AM, Dan Williams <dan.j.williams@intel.com> wrote: > The DAX implementation needs to protect new calls to ->direct_access() > and usage of its return value against unbind of the underlying block > device. Use blk_queue_enter()/blk_queue_exit() to either prevent > blk_cleanup_queue() from proceeding, or fail the dax_map_atomic() if the > request_queue is being torn down. > index f8e543839e5c..a480729c00ec 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, > loff_t start, loff_t end, get_block_t get_block, > struct buffer_head *bh) > { > - ssize_t retval = 0; > - loff_t pos = start; > - loff_t max = start; > - loff_t bh_max = start; > - void __pmem *addr; > + loff_t pos = start, max = start, bh_max = start; > + struct block_device *bdev = NULL; > + int rw = iov_iter_rw(iter), rc; fs/dax.c:138: warning: ‘rc’ may be used uninitialized in this function rc will be uninitialized if start == end, and the while loop below is never executed. I don't know whether it's 100% guaranteed this isn't the case. Note that the old retval was preinitialized to 0. > + long map_len = 0; > + unsigned long pfn; > + void __pmem *addr = NULL; > + void __pmem *kmap = (void __pmem *) ERR_PTR(-EIO); > bool hole = false; > bool need_wmb = false; > > - if (iov_iter_rw(iter) != WRITE) > + if (rw == READ) > end = min(end, i_size_read(inode)); > > while (pos < end) { > @@ -175,8 +219,9 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, > > if (need_wmb) > wmb_pmem(); > + dax_unmap_atomic(bdev, kmap); > > - return (pos == start) ? retval : pos - start; > + return (pos == start) ? rc : pos - start; > } Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
next prev parent reply other threads:[~2016-01-18 10:42 UTC|newest] Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-11-02 4:29 [PATCH v3 00/15] block, dax updates for 4.4 Dan Williams 2015-11-02 4:29 ` Dan Williams 2015-11-02 4:29 ` [PATCH v3 01/15] pmem, dax: clean up clear_pmem() Dan Williams 2015-11-02 4:29 ` Dan Williams 2015-11-02 4:29 ` [PATCH v3 02/15] dax: increase granularity of dax_clear_blocks() operations Dan Williams 2015-11-02 4:29 ` Dan Williams 2015-11-03 0:51 ` Dave Chinner 2015-11-03 0:51 ` Dave Chinner 2015-11-03 3:27 ` Dan Williams 2015-11-03 3:27 ` Dan Williams 2015-11-03 4:48 ` Dave Chinner 2015-11-03 4:48 ` Dave Chinner 2015-11-03 5:31 ` Dan Williams 2015-11-03 5:31 ` Dan Williams 2015-11-03 5:52 ` Dave Chinner 2015-11-03 5:52 ` Dave Chinner 2015-11-03 7:24 ` Dan Williams 2015-11-03 7:24 ` Dan Williams 2015-11-03 16:21 ` Jan Kara 2015-11-03 16:21 ` Jan Kara 2015-11-03 17:57 ` Ross Zwisler 2015-11-03 17:57 ` Ross Zwisler 2015-11-03 20:59 ` Dave Chinner 2015-11-03 20:59 ` Dave Chinner 2015-11-02 4:29 ` [PATCH v3 03/15] block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic() Dan Williams 2015-11-02 4:29 ` Dan Williams 2015-11-03 19:01 ` Ross Zwisler 2015-11-03 19:01 ` Ross Zwisler 2015-11-03 19:09 ` Jeff Moyer 2015-11-03 22:50 ` Dan Williams 2015-11-03 22:50 ` Dan Williams 2016-01-18 10:42 ` Geert Uytterhoeven [this message] 2016-01-18 10:42 ` Geert Uytterhoeven 2015-11-02 4:30 ` [PATCH v3 04/15] libnvdimm, pmem: move request_queue allocation earlier in probe Dan Williams 2015-11-02 4:30 ` Dan Williams 2015-11-03 19:15 ` Ross Zwisler 2015-11-03 19:15 ` Ross Zwisler 2015-11-02 4:30 ` [PATCH v3 05/15] libnvdimm, pmem: fix size trim in pmem_direct_access() Dan Williams 2015-11-02 4:30 ` Dan Williams 2015-11-03 19:32 ` Ross Zwisler 2015-11-03 19:32 ` Ross Zwisler 2015-11-03 21:39 ` Dan Williams 2015-11-03 21:39 ` Dan Williams 2015-11-02 4:30 ` [PATCH v3 06/15] um: kill pfn_t Dan Williams 2015-11-02 4:30 ` Dan Williams 2015-11-02 4:30 ` [PATCH v3 07/15] kvm: rename pfn_t to kvm_pfn_t Dan Williams 2015-11-02 4:30 ` Dan Williams 2015-11-02 4:30 ` [PATCH v3 08/15] mm, dax, pmem: introduce pfn_t Dan Williams 2015-11-02 4:30 ` Dan Williams 2015-11-02 16:30 ` Joe Perches 2015-11-02 16:30 ` Joe Perches 2015-11-02 4:30 ` [PATCH v3 09/15] block: notify queue death confirmation Dan Williams 2015-11-02 4:30 ` Dan Williams 2015-11-02 4:30 ` [PATCH v3 10/15] dax, pmem: introduce zone_device_revoke() and devm_memunmap_pages() Dan Williams 2015-11-02 4:30 ` Dan Williams 2015-11-02 4:30 ` [PATCH v3 11/15] block: introduce bdev_file_inode() Dan Williams 2015-11-02 4:30 ` Dan Williams 2015-11-02 4:30 ` [PATCH v3 12/15] block: enable dax for raw block devices Dan Williams 2015-11-02 4:30 ` Dan Williams 2015-11-02 4:30 ` [PATCH v3 13/15] block, dax: make dax mappings opt-in by default Dan Williams 2015-11-02 4:30 ` Dan Williams 2015-11-03 0:32 ` Dave Chinner 2015-11-03 0:32 ` Dave Chinner 2015-11-03 7:35 ` Dan Williams 2015-11-03 7:35 ` Dan Williams 2015-11-03 20:20 ` Dave Chinner 2015-11-03 20:20 ` Dave Chinner 2015-11-03 23:04 ` Dan Williams 2015-11-03 23:04 ` Dan Williams 2015-11-04 19:23 ` Dan Williams 2015-11-04 19:23 ` Dan Williams 2015-11-02 4:30 ` [PATCH v3 14/15] dax: dirty extent notification Dan Williams 2015-11-02 4:30 ` Dan Williams 2015-11-03 1:16 ` Dave Chinner 2015-11-03 1:16 ` Dave Chinner 2015-11-03 4:56 ` Dan Williams 2015-11-03 4:56 ` Dan Williams 2015-11-03 5:40 ` Dave Chinner 2015-11-03 5:40 ` Dave Chinner 2015-11-03 7:20 ` Dan Williams 2015-11-03 7:20 ` Dan Williams 2015-11-03 20:51 ` Dave Chinner 2015-11-03 20:51 ` Dave Chinner 2015-11-03 21:19 ` Dan Williams 2015-11-03 21:19 ` Dan Williams 2015-11-03 21:37 ` Ross Zwisler 2015-11-03 21:37 ` Ross Zwisler 2015-11-03 21:43 ` Dan Williams 2015-11-03 21:43 ` Dan Williams 2015-11-03 21:18 ` Ross Zwisler 2015-11-03 21:18 ` Ross Zwisler 2015-11-03 21:34 ` Dan Williams 2015-11-03 21:34 ` Dan Williams 2015-11-02 4:31 ` [PATCH v3 15/15] pmem: blkdev_issue_flush support Dan Williams 2015-11-02 4:31 ` Dan Williams
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