52a3974feb
Get and put the reference to the ctrl in the nvme_dev_open() and nvme_dev_release() before and after module get/put for ctrl in char device file operations. Introduce char_dev relase function, get/put the controller and module which allows us to fix the potential Oops which can be easily reproduced with a passthru ctrl (although the problem also exists with pure user access): Entering kdb (current=0xffff8887f8290000, pid 3128) on processor 30 Oops: (null) due to oops @ 0xffffffffa01019ad CPU: 30 PID: 3128 Comm: bash Tainted: G W OE 5.8.0-rc4nvme-5.9+ #35 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.4 RIP: 0010:nvme_free_ctrl+0x234/0x285 [nvme_core] Code: 57 10 a0 e8 73 bf 02 e1 ba 3d 11 00 00 48 c7 c6 98 33 10 a0 48 c7 c7 1d 57 10 a0 e8 5b bf 02 e1 8 RSP: 0018:ffffc90001d63de0 EFLAGS: 00010246 RAX: ffffffffa05c0440 RBX: ffff8888119e45a0 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff8888177e9550 RDI: ffff8888119e43b0 RBP: ffff8887d4768000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: ffffc90001d63c90 R12: ffff8888119e43b0 R13: ffff8888119e5108 R14: dead000000000100 R15: ffff8888119e5108 FS: 00007f1ef27b0740(0000) GS:ffff888817600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffa05c0470 CR3: 00000007f6bee000 CR4: 00000000003406e0 Call Trace: device_release+0x27/0x80 kobject_put+0x98/0x170 nvmet_passthru_ctrl_disable+0x4a/0x70 [nvmet] nvmet_passthru_enable_store+0x4c/0x90 [nvmet] configfs_write_file+0xe6/0x150 vfs_write+0xba/0x1e0 ksys_write+0x5f/0xe0 do_syscall_64+0x52/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f1ef1eb2840 Code: Bad RIP value. RSP: 002b:00007fffdbff0eb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f1ef1eb2840 RDX: 0000000000000002 RSI: 00007f1ef27d2000 RDI: 0000000000000001 RBP: 00007f1ef27d2000 R08: 000000000000000a R09: 00007f1ef27b0740 R10: 0000000000000001 R11: 0000000000000246 R12: 00007f1ef2186400 R13: 0000000000000002 R14: 0000000000000001 R15: 0000000000000000 With this patch fix we take the module ref count in nvme_dev_open() and release that ref count in newly introduced nvme_dev_release(). Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.