user/sven/linux.git/drivers, branch v3.18.24

tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c

2015-10-31T13:00:00Z

[ Upstream commit e81107d4c6bd098878af9796b24edc8d4a9524fd ] My colleague ran into a program stall on a x86_64 server, where n_tty_read() was waiting for data even if there was data in the buffer in the pty. kernel stack for the stuck process looks like below. #0 [ffff88303d107b58] __schedule at ffffffff815c4b20 #1 [ffff88303d107bd0] schedule at ffffffff815c513e #2 [ffff88303d107bf0] schedule_timeout at ffffffff815c7818 #3 [ffff88303d107ca0] wait_woken at ffffffff81096bd2 #4 [ffff88303d107ce0] n_tty_read at ffffffff8136fa23 #5 [ffff88303d107dd0] tty_read at ffffffff81368013 #6 [ffff88303d107e20] __vfs_read at ffffffff811a3704 #7 [ffff88303d107ec0] vfs_read at ffffffff811a3a57 #8 [ffff88303d107f00] sys_read at ffffffff811a4306 #9 [ffff88303d107f50] entry_SYSCALL_64_fastpath at ffffffff815c86d7 There seems to be two problems causing this issue. First, in drivers/tty/n_tty.c, __receive_buf() stores the data and updates ldata->commit_head using smp_store_release() and then checks the wait queue using waitqueue_active(). However, since there is no memory barrier, __receive_buf() could return without calling wake_up_interactive_poll(), and at the same time, n_tty_read() could start to wait in wait_woken() as in the following chart. __receive_buf() n_tty_read() ------------------------------------------------------------------------ if (waitqueue_active(&tty->read_wait)) /* Memory operations issued after the RELEASE may be completed before the RELEASE operation has completed */ add_wait_queue(&tty->read_wait, &wait); ... if (!input_available_p(tty, 0)) { smp_store_release(&ldata->commit_head, ldata->read_head); ... timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, timeout); ------------------------------------------------------------------------ The second problem is that n_tty_read() also lacks a memory barrier call and could also cause __receive_buf() to return without calling wake_up_interactive_poll(), and n_tty_read() to wait in wait_woken() as in the chart below. __receive_buf() n_tty_read() ------------------------------------------------------------------------ spin_lock_irqsave(&q->lock, flags); /* from add_wait_queue() */ ... if (!input_available_p(tty, 0)) { /* Memory operations issued after the RELEASE may be completed before the RELEASE operation has completed */ smp_store_release(&ldata->commit_head, ldata->read_head); if (waitqueue_active(&tty->read_wait)) __add_wait_queue(q, wait); spin_unlock_irqrestore(&q->lock,flags); /* from add_wait_queue() */ ... timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, timeout); ------------------------------------------------------------------------ There are also other places in drivers/tty/n_tty.c which have similar calls to waitqueue_active(), so instead of adding many memory barrier calls, this patch simply removes the call to waitqueue_active(), leaving just wake_up*() behind. This fixes both problems because, even though the memory access before or after the spinlocks in both wake_up*() and add_wait_queue() can sneak into the critical section, it cannot go past it and the critical section assures that they will be serialized (please see "INTER-CPU ACQUIRING BARRIER EFFECTS" in Documentation/memory-barriers.txt for a better explanation). Moreover, the resulting code is much simpler. Latency measurement using a ping-pong test over a pty doesn't show any visible performance drop. Signed-off-by: Kosuke Tatsukawa Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

Revert "tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c"

2015-10-31T12:54:32Z

This reverts commit af32cc7bde6304dac92e6a74fe4b2cc8120cb29a. The commit was incorrectly backported and was causing hangs. Reported-by: Corey Wright Signed-off-by: Sasha Levin

3w-9xxx: don't unmap bounce buffered commands

2015-10-28T07:52:26Z

[ Upstream commit 15e3d5a285ab9283136dba34bbf72886d9146706 ] 3w controller don't dma map small single SGL entry commands but instead bounce buffer them. Add a helper to identify these commands and don't call scsi_dma_unmap for them. Based on an earlier patch from James Bottomley. Fixes: 118c85 ("3w-9xxx: fix command completion race") Reported-by: Tóth Attila Tested-by: Tóth Attila Signed-off-by: Christoph Hellwig Acked-by: Adam Radford Signed-off-by: James Bottomley Signed-off-by: Sasha Levin

md: flush ->event_work before stopping array.

2015-10-28T02:14:57Z

[ Upstream commit ee5d004fd0591536a061451eba2b187092e9127c ] The 'event_work' worker used by dm-raid may still be running when the array is stopped. This can result in an oops. So flush the workqueue on which it is run after detaching and before destroying the device. Reported-by: Heinz Mauelshagen Signed-off-by: NeilBrown Cc: stable@vger.kernel.org (2.6.38+ please delay 2 weeks after -final release) Fixes: 9d09e663d550 ("dm: raid456 basic support") Signed-off-by: Sasha Levin

Revert "iio: bmg160: IIO_BUFFER and IIO_TRIGGERED_BUFFER are required"

2015-10-28T02:14:56Z

[ Upstream commit HEAD ] This reverts commit 279c039ca63acbd69e69d6d7ddfed50346fb2185 which was commit 06d2f6ca5a38abe92f1f3a132b331eee773868c3 upstream as it should not have been applied. Reported-by: Luis Henriques Cc: Markus Pargmann Cc: Srinivas Pandruvada Cc: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 934d9b907aeec5f344ca801ed7361551199dfc69) Signed-off-by: Sasha Levin

mm: check if section present during memory block registering

2015-10-28T02:14:54Z

[ Upstream commit 04697858d89e4bf2650364f8d6956e2554e8ef88 ] Tony Luck found on his setup, if memory block size 512M will cause crash during booting. BUG: unable to handle kernel paging request at ffffea0074000020 IP: get_nid_for_pfn+0x17/0x40 PGD 128ffcb067 PUD 128ffc9067 PMD 0 Oops: 0000 [#1] SMP Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.2.0-rc8 #1 ... Call Trace: ? register_mem_sect_under_node+0x66/0xe0 register_one_node+0x17b/0x240 ? pci_iommu_alloc+0x6e/0x6e topology_init+0x3c/0x95 do_one_initcall+0xcd/0x1f0 The system has non continuous RAM address: BIOS-e820: [mem 0x0000001300000000-0x0000001cffffffff] usable BIOS-e820: [mem 0x0000001d70000000-0x0000001ec7ffefff] usable BIOS-e820: [mem 0x0000001f00000000-0x0000002bffffffff] usable BIOS-e820: [mem 0x0000002c18000000-0x0000002d6fffefff] usable BIOS-e820: [mem 0x0000002e00000000-0x00000039ffffffff] usable So there are start sections in memory block not present. For example: memory block : [0x2c18000000, 0x2c20000000) 512M first three sections are not present. The current register_mem_sect_under_node() assume first section is present, but memory block section number range [start_section_nr, end_section_nr] would include not present section. For arch that support vmemmap, we don't setup memmap for struct page area within not present sections area. So skip the pfn range that belong to absent section. [akpm@linux-foundation.org: simplification] [rientjes@google.com: more simplification] Fixes: bdee237c0343 ("x86: mm: Use 2GB memory block size on large memory x86-64 systems") Fixes: 982792c782ef ("x86, mm: probe memory block size for generic x86 64bit") Signed-off-by: Yinghai Lu Signed-off-by: David Rientjes Reported-by: Tony Luck Tested-by: Tony Luck Cc: Greg KH Cc: Ingo Molnar Tested-by: David Rientjes Cc: [3.15+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

drivercore: Fix unregistration path of platform devices

2015-10-28T02:14:53Z

[ Upstream commit 7f5dcaf1fdf289767a126a0a5cc3ef39b5254b06 ] The unregister path of platform_device is broken. On registration, it will register all resources with either a parent already set, or type==IORESOURCE_{IO,MEM}. However, on unregister it will release everything with type==IORESOURCE_{IO,MEM}, but ignore the others. There are also cases where resources don't get registered in the first place, like with devices created by of_platform_populate()*. Fix the unregister path to be symmetrical with the register path by checking the parent pointer instead of the type field to decide which resources to unregister. This is safe because the upshot of the registration path algorithm is that registered resources have a parent pointer, and non-registered resources do not. * It can be argued that of_platform_populate() should be registering it's resources, and they argument has some merit. However, there are quite a few platforms that end up broken if we try to do that due to overlapping resources in the device tree. Until that is fixed, we need to solve the immediate problem. Cc: Pantelis Antoniou Cc: Wolfram Sang Cc: Rob Herring Cc: Greg Kroah-Hartman Cc: Ricardo Ribalda Delgado Signed-off-by: Grant Likely Tested-by: Ricardo Ribalda Delgado Tested-by: Wolfram Sang Cc: stable@vger.kernel.org Signed-off-by: Rob Herring Signed-off-by: Sasha Levin

of/address: Don't loop forever in of_find_matching_node_by_address().

2015-10-28T02:14:51Z

[ Upstream commit 3a496b00b6f90c41bd21a410871dfc97d4f3c7ab ] If the internal call to of_address_to_resource() fails, we end up looping forever in of_find_matching_node_by_address(). This can be caused by a defective device tree, or calling with an incorrect matches argument. Fix by calling of_find_matching_node() unconditionally at the end of the loop. Signed-off-by: David Daney Cc: stable@vger.kernel.org Signed-off-by: Rob Herring Signed-off-by: Sasha Levin

auxdisplay: ks0108: fix refcount

2015-10-28T02:14:50Z

[ Upstream commit bab383de3b84e584b0f09227151020b2a43dc34c ] parport_find_base() will implicitly do parport_get_port() which increases the refcount. Then parport_register_device() will again increment the refcount. But while unloading the module we are only doing parport_unregister_device() decrementing the refcount only once. We add an parport_put_port() to neutralize the effect of parport_get_port(). Cc: # 2.6.32+ Signed-off-by: Sudip Mukherjee Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

devres: fix devres_get()

2015-10-28T02:14:48Z

[ Upstream commit 64526370d11ce8868ca495723d595b61e8697fbf ] Currently, devres_get() passes devres_free() the pointer to devres, but devres_free() should be given with the pointer to resource data. Fixes: 9ac7849e35f7 ("devres: device resource management") Signed-off-by: Masahiro Yamada Acked-by: Tejun Heo Cc: stable # 2.6.21+ Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin