kernel/linux.git/include/linux, branch v3.8.7

spinlocks and preemption points need to be at least compiler barriers

2013-04-12T16:52:09+00:00

commit 386afc91144b36b42117b0092893f15bc8798a80 upstream. In UP and non-preempt respectively, the spinlocks and preemption disable/enable points are stubbed out entirely, because there is no regular code that can ever hit the kind of concurrency they are meant to protect against. However, while there is no regular code that can cause scheduling, we _do_ end up having some exceptional (literally!) code that can do so, and that we need to make sure does not ever get moved into the critical region by the compiler. In particular, get_user() and put_user() is generally implemented as inline asm statements (even if the inline asm may then make a call instruction to call out-of-line), and can obviously cause a page fault and IO as a result. If that inline asm has been scheduled into the middle of a preemption-safe (or spinlock-protected) code region, we obviously lose. Now, admittedly this is *very* unlikely to actually ever happen, and we've not seen examples of actual bugs related to this. But partly exactly because it's so hard to trigger and the resulting bug is so subtle, we should be extra careful to get this right. So make sure that even when preemption is disabled, and we don't have to generate any actual *code* to explicitly tell the system that we are in a preemption-disabled region, we need to at least tell the compiler not to move things around the critical region. This patch grew out of the same discussion that caused commits 79e5f05edcbf ("ARC: Add implicit compiler barrier to raw_local_irq* functions") and 3e2e0d2c222b ("tile: comment assumption about __insn_mtspr for ") to come about. Note for stable: use discretion when/if applying this. As mentioned, this bug may never have actually bitten anybody, and gcc may never have done the required code motion for it to possibly ever trigger in practice. Signed-off-by: Linus Torvalds Cc: Steven Rostedt Cc: Peter Zijlstra Signed-off-by: Greg Kroah-Hartman

libata: Set max sector to 65535 for Slimtype DVD A DS8A8SH drive

2013-04-12T16:52:06+00:00

commit a32450e127fc6e5ca6d958ceb3cfea4d30a00846 upstream. The Slimtype DVD A DS8A8SH drive locks up when max sector is smaller than 65535, and the blow backtrace is observed on locking up: INFO: task flush-8:32:1130 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. flush-8:32 D ffffffff8180cf60 0 1130 2 0x00000000 ffff880273aef618 0000000000000046 0000000000000005 ffff880273aee000 ffff880273aee000 ffff880273aeffd8 ffff880273aee010 ffff880273aee000 ffff880273aeffd8 ffff880273aee000 ffff88026e842ea0 ffff880274a10000 Call Trace: [] schedule+0x5d/0x70 [] io_schedule+0x8c/0xd0 [] get_request+0x731/0x7d0 [] ? cfq_allow_merge+0x50/0x90 [] ? wake_up_bit+0x40/0x40 [] ? bio_attempt_back_merge+0x33/0x110 [] blk_queue_bio+0x23a/0x3f0 [] generic_make_request+0xc6/0x120 [] submit_bio+0x138/0x160 [] ? bio_alloc_bioset+0x96/0x120 [] submit_bh+0x1f1/0x220 [] __block_write_full_page+0x228/0x340 [] ? attach_nobh_buffers+0xc0/0xc0 [] ? I_BDEV+0x10/0x10 [] ? I_BDEV+0x10/0x10 [] block_write_full_page_endio+0xe6/0x100 [] block_write_full_page+0x15/0x20 [] blkdev_writepage+0x18/0x20 [] __writepage+0x17/0x40 [] write_cache_pages+0x34a/0x4a0 [] ? set_page_dirty+0x70/0x70 [] generic_writepages+0x51/0x80 [] do_writepages+0x20/0x50 [] __writeback_single_inode+0xa6/0x2b0 [] writeback_sb_inodes+0x311/0x4d0 [] __writeback_inodes_wb+0x86/0xd0 [] wb_writeback+0x1a3/0x330 [] ? _raw_spin_lock_irqsave+0x3f/0x50 [] ? get_nr_inodes+0x52/0x70 [] wb_do_writeback+0x1dc/0x260 [] ? schedule_timeout+0x204/0x240 [] bdi_writeback_thread+0x102/0x2b0 [] ? wb_do_writeback+0x260/0x260 [] kthread+0xc0/0xd0 [] ? kthread_worker_fn+0x1b0/0x1b0 [] ret_from_fork+0x7c/0xb0 [] ? kthread_worker_fn+0x1b0/0x1b0 The above trace was triggered by "dd if=/dev/zero of=/dev/sr0 bs=2048 count=32768" It was previously working by accident, since another bug introduced by 4dce8ba94c7 (libata: Use 'bool' return value for ata_id_XXX) caused all drives to use maxsect=65535. Signed-off-by: Shan Hai Signed-off-by: Jeff Garzik Signed-off-by: Greg Kroah-Hartman

libata: Use integer return value for atapi_command_packet_set

2013-04-12T16:52:05+00:00

commit d8668fcb0b257d9fdcfbe5c172a99b8d85e1cd82 upstream. The function returns type of ATAPI drives so it should return integer value. The commit 4dce8ba94c7 (libata: Use 'bool' return value for ata_id_XXX) since v2.6.39 changed the type of return value from int to bool, the change would cause all of the ATAPI class drives to be treated as TYPE_TAPE and the max_sectors of the drives to be set to 65535 because of the commit f8d8e5799b7(libata: increase 128 KB / cmd limit for ATAPI tape drives), for the function would return true for all ATAPI class drives and the TYPE_TAPE is defined as 0x01. Signed-off-by: Shan Hai Signed-off-by: Jeff Garzik Signed-off-by: Greg Kroah-Hartman

thermal: shorten too long mcast group name

2013-04-05T16:26:17+00:00

[ Upstream commits 73214f5d9f33b79918b1f7babddd5c8af28dd23d and f1e79e208076ffe7bad97158275f1c572c04f5c7, the latter adds an assertion to genetlink to prevent this from happening again in the future. ] The original name is too long. Signed-off-by: Masatake YAMATO Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

USB: serial: add modem-status-change wait queue

2013-04-05T16:26:03+00:00

commit e5b33dc9d16053c2ae4c2c669cf008829530364b upstream. Add modem-status-change wait queue to struct usb_serial_port that subdrivers can use to implement TIOCMIWAIT. Currently subdrivers use a private wait queue which may have been released when waking up after device disconnected. Note that we're adding a new wait queue rather than reusing the tty-port one as we do not want to get woken up at hangup (yet). Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

userns: Restrict when proc and sysfs can be mounted

2013-04-05T16:26:02+00:00

commit 87a8ebd637dafc255070f503909a053cf0d98d3f upstream. Only allow unprivileged mounts of proc and sysfs if they are already mounted when the user namespace is created. proc and sysfs are interesting because they have content that is per namespace, and so fresh mounts are needed when new namespaces are created while at the same time proc and sysfs have content that is shared between every instance. Respect the policy of who may see the shared content of proc and sysfs by only allowing new mounts if there was an existing mount at the time the user namespace was created. In practice there are only two interesting cases: proc and sysfs are mounted at their usual places, proc and sysfs are not mounted at all (some form of mount namespace jail). Acked-by: Serge Hallyn Signed-off-by: "Eric W. Biederman" Signed-off-by: Greg Kroah-Hartman

vfs: Add a mount flag to lock read only bind mounts

2013-04-05T16:26:01+00:00

commit 90563b198e4c6674c63672fae1923da467215f45 upstream. When a read-only bind mount is copied from mount namespace in a higher privileged user namespace to a mount namespace in a lesser privileged user namespace, it should not be possible to remove the the read-only restriction. Add a MNT_LOCK_READONLY mount flag to indicate that a mount must remain read-only. Acked-by: Serge Hallyn Signed-off-by: "Eric W. Biederman" Signed-off-by: Greg Kroah-Hartman

userns: Don't allow creation if the user is chrooted

2013-04-05T16:26:01+00:00

commit 3151527ee007b73a0ebd296010f1c0454a919c7d upstream. Guarantee that the policy of which files may be access that is established by setting the root directory will not be violated by user namespaces by verifying that the root directory points to the root of the mount namespace at the time of user namespace creation. Changing the root is a privileged operation, and as a matter of policy it serves to limit unprivileged processes to files below the current root directory. For reasons of simplicity and comprehensibility the privilege to change the root directory is gated solely on the CAP_SYS_CHROOT capability in the user namespace. Therefore when creating a user namespace we must ensure that the policy of which files may be access can not be violated by changing the root directory. Anyone who runs a processes in a chroot and would like to use user namespace can setup the same view of filesystems with a mount namespace instead. With this result that this is not a practical limitation for using user namespaces. Acked-by: Serge Hallyn Reported-by: Andy Lutomirski Signed-off-by: "Eric W. Biederman" Signed-off-by: Greg Kroah-Hartman

net: cdc_ncm, cdc_mbim: allow user to prefer NCM for backwards compatibility

2013-03-28T19:17:16+00:00

[ Upstream commit 1e8bbe6cd02fc300c88bd48244ce61ad9c7d1776 ] commit bd329e1 ("net: cdc_ncm: do not bind to NCM compatible MBIM devices") introduced a new policy, preferring MBIM for dual NCM/MBIM functions if the cdc_mbim driver was enabled. This caused a regression for users wanting to use NCM. Devices implementing NCM backwards compatibility according to section 3.2 of the MBIM v1.0 specification allow either NCM or MBIM on a single USB function, using different altsettings. The cdc_ncm and cdc_mbim drivers will both probe such functions, and must agree on a common policy for selecting either MBIM or NCM. Until now, this policy has been set at build time based on CONFIG_USB_NET_CDC_MBIM. Use a module parameter to set the system policy at runtime, allowing the user to prefer NCM on systems with the cdc_mbim driver. Cc: Greg Suarez Cc: Alexey Orishko Reported-by: Geir Haatveit Reported-by: Tommi Kyntola Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=54791 Signed-off-by: Bjørn Mork Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

skb: Propagate pfmemalloc on skb from head page only

2013-03-28T19:17:09+00:00

[ Upstream commit cca7af3889bfa343d33d5e657a38d876abd10e58 ] Hi. I'm trying to send big chunks of memory from application address space via TCP socket using vmsplice + splice like this mem = mmap(128Mb); vmsplice(pipe[1], mem); /* splice memory into pipe */ splice(pipe[0], tcp_socket); /* send it into network */ When I'm lucky and a huge page splices into the pipe and then into the socket _and_ client and server ends of the TCP connection are on the same host, communicating via lo, the whole connection gets stuck! The sending queue becomes full and app stops writing/splicing more into it, but the receiving queue remains empty, and that's why. The __skb_fill_page_desc observes a tail page of a huge page and erroneously propagates its page->pfmemalloc value onto socket (the pfmemalloc on tail pages contain garbage). Then this skb->pfmemalloc leaks through lo and due to the tcp_v4_rcv sk_filter if (skb->pfmemalloc && !sock_flag(sk, SOCK_MEMALLOC)) /* true */ return -ENOMEM goto release_and_discard; no packets reach the socket. Even TCP re-transmits are dropped by this, as skb cloning clones the pfmemalloc flag as well. That said, here's the proper page->pfmemalloc propagation onto socket: we must check the huge-page's head page only, other pages' pfmemalloc and mapping values do not contain what is expected in this place. However, I'm not sure whether this fix is _complete_, since pfmemalloc propagation via lo also oesn't look great. Both, bit propagation from page to skb and this check in sk_filter, were introduced by c48a11c7 (netvm: propagate page->pfmemalloc to skb), in v3.5 so Mel and stable@ are in Cc. Signed-off-by: Pavel Emelyanov Acked-by: Eric Dumazet Acked-by: Mel Gorman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman