27 Oct, 2010
5 commits
-
Structure info is copied to userland with some padding fields unitialized.
It leads to leaking of stack memory.[akpm@linux-foundation.org: remove now-unneeded zeroing of info->hi_ireqfreq]
Signed-off-by: Vasiliy Kulikov
Cc: Clemens Ladisch
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fix the following style problems:
WARNING: Use #include instead of
WARNING: Use #include instead of
ERROR: code indent should use tabs where possible
ERROR: do not initialise statics to 0 or NULLSigned-off-by: Jaswinder Singh Rajput
Cc: Clemens Ladisch
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Jaswinder Singh Rajput wrote:
> By executing Documentation/timers/hpet_example.c
>
> for polling, I requested for 3 iterations but it seems iteration work
> for only 2 as first expired time is always very small.
>
> # ./hpet_example poll /dev/hpet 10 3
> -hpet: executing poll
> hpet_poll: info.hi_flags 0x0
> hpet_poll: expired time = 0x13
> hpet_poll: revents = 0x1
> hpet_poll: data 0x1
> hpet_poll: expired time = 0x1868c
> hpet_poll: revents = 0x1
> hpet_poll: data 0x1
> hpet_poll: expired time = 0x18645
> hpet_poll: revents = 0x1
> hpet_poll: data 0x1Clearing the HPET interrupt enable bit disables interrupt generation
but does not disable the timer, so the interrupt status bit will still
be set when the timer elapses. If another interrupt arrives before
the timer has been correctly programmed (due to some other device on
the same interrupt line, or CONFIG_DEBUG_SHIRQ), this results in an
extra unwanted interrupt event because the status bit is likely to be
set from comparator matches that happened before the device was opened.Therefore, we have to ensure that the interrupt status bit is and
stays cleared until we actually program the timer.Signed-off-by: Clemens Ladisch
Reported-by: Jaswinder Singh Rajput
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: john stultz
Cc: Bob Picco
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
When the initialization code in hpet finds a memory resource and does not
find an IRQ, it does not unmap the memory resource previously mapped.There are buggy BIOSes which report resources exactly like this and what
is worse the memory region bases point to normal RAM. This normally would
not matter since the space is not touched. But when PAT is turned on,
ioremap causes the page to be uncached and sets this bit in page->flags.Then when the page is about to be used by the allocator, it is reported
as:BUG: Bad page state in process md5sum pfn:3ed00
page:ffffea0000dbd800 count:0 mapcount:0 mapping:(null) index:0x0
page flags: 0x20000001000000(uncached)
Pid: 7956, comm: md5sum Not tainted 2.6.34-12-desktop #1
Call Trace:
[] bad_page+0xb1/0x100
[] prep_new_page+0x1a5/0x1c0
[] get_page_from_freelist+0x3a1/0x640
[] __alloc_pages_nodemask+0x10f/0x6b0
...In this particular case:
1) HPET returns 3ed00000 as memory region base, but it is not in
reserved ranges reported by the BIOS (excerpt):
BIOS-e820: 0000000000100000 - 00000000af6cf000 (usable)
BIOS-e820: 00000000af6cf000 - 00000000afdcf000 (reserved)2) there is no IRQ resource reported by HPET method. On the other
hand, the Intel HPET specs (1.0a) says (3.2.5.1):
_CRS (
// Report 1K of memory consumed by this Timer Block
memory range consumed
// Optional: only used if BIOS allocates Interrupts [1]
IRQs consumed
)[1] For case where Timer Block is configured to consume IRQ0/IRQ8 AND
Legacy 8254/Legacy RTC hardware still exists, the device objects
associated with 8254 & RTC devices should not report IRQ0/IRQ8 as
"consumed resources".So in theory we should check whether if it is the case and use those
interrupts instead.Anyway the address reported by the BIOS here is bogus, so non-presence
of IRQ doesn't mean the "optional" part in point 2).Since I got no reply previously, fix this by simply unmapping the space
when IRQ is not found and memory region was mapped previously. It would
be probably more safe to walk the resources again and unmap appropriately
depending on type. But as we now use only ioremap for both 2 memory
resource types, it is not necessarily needed right now.Addresses https://bugzilla.novell.com/show_bug.cgi?id=629908
Reported-by: Olaf Hering
Signed-off-by: Jiri Slaby
Acked-by: Clemens Ladisch
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Unloading ipmi module can trigger following error. (if
CONFIG_DEBUG_SPINLOCK=y)[ 9633.779590] BUG: spinlock bad magic on CPU#1, rmmod/7170
[ 9633.779606] lock: f41f5414, .magic: 00000000, .owner:
/-1, .owner_cpu: 0
[ 9633.779626] Pid: 7170, comm: rmmod Not tainted
2.6.36-rc7-11474-gb71eb1e-dirty #328
[ 9633.779644] Call Trace:
[ 9633.779657] [] ? printk+0x18/0x1c
[ 9633.779672] [] spin_bug+0xa3/0xf0
[ 9633.779685] [] do_raw_spin_lock+0x7d/0x160
[ 9633.779702] [] ? release_sysfs_dirent+0x47/0xb0
[ 9633.779718] [] ? sysfs_addrm_finish+0xa8/0xd0
[ 9633.779734] [] _raw_spin_lock_irqsave+0xc/0x20
[ 9633.779752] [] cleanup_one_si+0x6a/0x200 [ipmi_si]
[ 9633.779768] [] ? sysfs_hash_and_remove+0x72/0x80
[ 9633.779786] [] ipmi_pnp_remove+0xd/0xf [ipmi_si]
[ 9633.779802] [] pnp_device_remove+0x1b/0x40Fix this by initializing spinlocks in a smi_info_alloc() helper function,
right after memory allocation and clearing.Signed-off-by: Eric Dumazet
Acked-by: David Miller
Cc: Yinghai Lu
Acked-by: Corey Minyard
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
25 Oct, 2010
4 commits
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* 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6: (48 commits)
[S390] topology: export cpu topology via proc/sysinfo
[S390] topology: move topology sysinfo code
[S390] topology: clean up facility detection
[S390] cleanup facility list handling
[S390] enable ARCH_DMA_ADDR_T_64BIT with 64BIT
[S390] dasd: ignore unsolicited interrupts for DIAG
[S390] kvm: Enable z196 instruction facilities
[S390] dasd: fix unsolicited interrupt recognition
[S390] dasd: fix use after free in dbf
[S390] kvm: Fix badness at include/asm/mmu_context.h:83
[S390] cio: fix I/O cancel function
[S390] topology: change default
[S390] smp: use correct cpu address in print_cpu_info()
[S390] remove ieee_instruction_pointer from thread_struct
[S390] cleanup system call parameter setup
[S390] correct alignment of cpuid structure
[S390] cleanup lowcore access from external interrupts
[S390] cleanup lowcore access from program checks
[S390] pgtable: move pte_mkhuge() from hugetlb.h to pgtable.h
[S390] fix SIGBUS handling
... -
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: (75 commits)
Input: wacom - specify Cinitq supported tools
Input: ab8500-ponkey - fix IRQ freeing in error path
Input: adp5588-keys - use more obvious i2c_device_id name string
Input: ad7877 - switch to using threaded IRQ
Input: ad7877 - use attribute group to control visibility of attributes
Input: serio - add support for PS2Mult multiplexer protocol
Input: wacom - properly enable runtime PM
Input: ad7877 - filter events where pressure is beyond the maximum
Input: ad7877 - implement EV_KEY:BTN_TOUCH reporting
Input: ad7877 - implement specified chip select behavior
Input: hp680_ts_input - use cancel_delayed_work_sync()
Input: mousedev - correct lockdep annotation
Input: ads7846 - switch to using threaded IRQ
Input: serio - support multiple child devices per single parent
Input: synaptics - simplify pass-through port handling
Input: add ROHM BU21013 touch panel controller support
Input: omap4-keypad - wake-up on events & long presses
Input: omap4-keypad - fix interrupt line configuration
Input: omap4-keypad - SYSCONFIG register configuration
Input: omap4-keypad - use platform device helpers
... -
If the iucv_register() functions fails, the error recovery calls
iucv_unregister() which might cause the following stack backtrace:( show_trace+0xee/0x144)
panic+0xb6/0x248
die+0x15a/0x16c
do_no_context+0xa6/0xe4
do_protection_exception+0x2e8/0x3a4
pgm_exit+0x0/0x14
iucv_unregister+0x5a/0x17c
( iucv_unregister+0x4a/0x17c)
hvc_iucv_init+0x228/0x5dc
do_one_initcall+0x3e/0x19c
kernel_init+0x28e/0x404
kernel_thread_starter+0x6/0xc
kernel_thread_starter+0x0/0xcRemove the call to iucv_unregister() and remove the goto label
as unregistering is the last step in the hvc_iucv initialization.
If iucv_register() fails, simply clean up hvc terminals and free
resources.Signed-off-by: Hendrik Brueckner
Signed-off-by: Martin Schwidefsky -
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (39 commits)
Update broken web addresses in arch directory.
Update broken web addresses in the kernel.
Revert "drivers/usb: Remove unnecessary return's from void functions" for musb gadget
Revert "Fix typo: configuation => configuration" partially
ida: document IDA_BITMAP_LONGS calculation
ext2: fix a typo on comment in ext2/inode.c
drivers/scsi: Remove unnecessary casts of private_data
drivers/s390: Remove unnecessary casts of private_data
net/sunrpc/rpc_pipe.c: Remove unnecessary casts of private_data
drivers/infiniband: Remove unnecessary casts of private_data
drivers/gpu/drm: Remove unnecessary casts of private_data
kernel/pm_qos_params.c: Remove unnecessary casts of private_data
fs/ecryptfs: Remove unnecessary casts of private_data
fs/seq_file.c: Remove unnecessary casts of private_data
arm: uengine.c: remove C99 comments
arm: scoop.c: remove C99 comments
Fix typo configue => configure in comments
Fix typo: configuation => configuration
Fix typo interrest[ing|ed] => interest[ing|ed]
Fix various typos of valid in comments
...Fix up trivial conflicts in:
drivers/char/ipmi/ipmi_si_intf.c
drivers/usb/gadget/rndis.c
net/irda/irnet/irnet_ppp.c
23 Oct, 2010
13 commits
-
* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6: (49 commits)
serial8250: ratelimit "too much work" error
serial: bfin_sport_uart: speed up sport RX sample rate to be 3% faster
serial: abstraction for 8250 legacy ports
serial/imx: check that the buffer is non-empty before sending it out
serial: mfd: add more baud rates support
jsm: Remove the uart port on errors
Alchemy: Add UART PM methods.
8250: allow platforms to override PM hook.
altera_uart: Don't use plain integer as NULL pointer
altera_uart: Fix missing prototype for registering an early console
altera_uart: Fixup type usage of port flags
altera_uart: Make it possible to use Altera UART and 8250 ports together
altera_uart: Add support for different address strides
altera_uart: Add support for getting mapbase and IRQ from resources
altera_uart: Add support for polling mode (IRQ-less)
serial: Factor out uart_poll_timeout() from 8250 driver
serial: mark the 8250 driver as maintained
serial: 8250: Don't delay after transmitter is ready.
tty: MAINTAINERS: add drivers/serial/jsm/ as maintained driver
vcs: invoke the vt update callback when /dev/vcs* is written to
... -
* 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
vfs: make no_llseek the default
vfs: don't use BKL in default_llseek
llseek: automatically add .llseek fop
libfs: use generic_file_llseek for simple_attr
mac80211: disallow seeks in minstrel debug code
lirc: make chardev nonseekable
viotape: use noop_llseek
raw: use explicit llseek file operations
ibmasmfs: use generic_file_llseek
spufs: use llseek in all file operations
arm/omap: use generic_file_llseek in iommu_debug
lkdtm: use generic_file_llseek in debugfs
net/wireless: use generic_file_llseek in debugfs
drm: use noop_llseek -
* 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
block: autoconvert trivial BKL users to private mutex
drivers: autoconvert trivial BKL users to private mutex
ipmi: autoconvert trivial BKL users to private mutex
mac: autoconvert trivial BKL users to private mutex
mtd: autoconvert trivial BKL users to private mutex
scsi: autoconvert trivial BKL users to private mutexFix up trivial conflicts (due to addition of private mutex right next to
deletion of a version string) in drivers/char/pcmcia/cm40[04]0_cs.c -
* 'config' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
BKL: introduce CONFIG_BKL.
dabusb: remove the BKL
sunrpc: remove the big kernel lock
init/main.c: remove BKL notations
blktrace: remove the big kernel lock
rtmutex-tester: make it build without BKL
dvb-core: kill the big kernel lock
dvb/bt8xx: kill the big kernel lock
tlclk: remove big kernel lock
fix rawctl compat ioctls breakage on amd64 and itanic
uml: kill big kernel lock
parisc: remove big kernel lock
cris: autoconvert trivial BKL users
alpha: kill big kernel lock
isapnp: BKL removal
s390/block: kill the big kernel lock
hpet: kill BKL, add compat_ioctl -
A notifier chain is called whenever the vt code modifies a terminal
content, except for one case which is when the modification comes
through writes to /dev/vcs* devices. Let's add the missing notifier
invocation at the end of vcs_write() for that case too.Signed-off-by: Nicolas Pitre
Cc: Alan Cox
Signed-off-by: Greg Kroah-Hartman -
The /dev/vcs* devices are used, amongst other things, by accessibility
applications such as BRLTTY to display the screen content onto refreshable
braille displays. Currently this is performed by constantly reading from
/dev/vcsa0 whether or not the screen content has changed. Given the
default braille refresh rate of 25 times per second, this easily qualifies
as the biggest source of wake-up events preventing laptops from entering
deeper power saving states.To avoid this periodic polling, let's add support for select()/poll() and
SIGIO with the /dev/vcs* devices. The implemented semantic is to report
data availability whenever the corresponding vt has seen some update after
the last read() operation. The application still has to lseek() back
as usual in order to read() the new data.Not to create unwanted overhead, the needed data structure is allocated
and the vt notification callback is registered only when the poll or
fasync method is invoked for the first time per file instance.Signed-off-by: Nicolas Pitre
Cc: Andrew Morton
Acked-by: Alan Cox
Signed-off-by: Greg Kroah-Hartman -
Again basically cut and paste
Convert the main driver set to use the hooks for GICOUNT
Signed-off-by: Alan Cox
Signed-off-by: Greg Kroah-Hartman -
Dan Rosenberg noted that various drivers return the struct with uncleared
fields. Instead of spending forever trying to stomp all the drivers that
get it wrong (and every new driver) do the job in one place.This first patch adds the needed operations and hooks them up, including
the needed USB midlayer and serial core plumbing.Signed-off-by: Alan Cox
Signed-off-by: Greg Kroah-Hartman -
Function tty_register_device may return ERR_PTR(...). Check for it.
Signed-off-by: Vasiliy Kulikov
Signed-off-by: Greg Kroah-Hartman -
Vasiliy found that pci_disable_device is not called on fail paths in
mxser_probe. Actually, it is called from nowhere in the driver.There are three changes needed:
1) don't use pseudo-generic mxser_release_res. Let's use it only from
ISA paths from now on. All the pci stuff is moved to probe and
remove PCI-related functions.
2) reorder fail-paths in the probe function so that it makes sense and
we can call them from the sequential code naturally (the further we
are the earlier label we go to).
3) add pci_disable_device both to mxser_probe and mxser_remove.There is a nit of adding CONFIG_PCI ifdef to mxser_remove. it is
because this driver supports ISA-only compilations and it would choke
up on the newly added calls now.Signed-off-by: Jiri Slaby
Cc: Kulikov Vasiliy
Signed-off-by: Greg Kroah-Hartman -
Ttyprintk is a pseudo TTY driver, which allows users to make printk
messages, via output to ttyprintk device. It is possible to store
"console" messages inline with kernel messages for better analyses of
the boot process, for example.Signed-off-by: Samo Pogacnik
Acked-by: Alan Cox
Signed-off-by: Greg Kroah-Hartman -
This patch removes __GFP_NOFAIL use from tty_add_file() and adds proper error
handling to the call-sites of the function.Cc: Andrew Morton
Cc: Alan Cox
Cc: Arnd Bergmann
Signed-off-by: Pekka Enberg
Acked-by: David Rientjes
Signed-off-by: Greg Kroah-Hartman -
Some device drivers (mostly tty line disciplines) would like to have way
know a struct device instance corresponding to passed tty_struct. Add
a struct device pointer to struct tty_struct and populate it during
initialize_tty_struct().Signed-off-by: Dmitry Eremin-Solenikov
Acked-by: Alan Cox
Signed-off-by: Greg Kroah-Hartman
22 Oct, 2010
4 commits
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* git://git.kernel.org/pub/scm/linux/kernel/git/brodo/pcmcia-2.6: (22 commits)
pcmcia: synclink_cs: fix information leak to userland
pcmcia: don't call flush_scheduled_work() spuriously
serial_cs: drop spurious flush_scheduled_work() call
pcmcia/yenta: guide users in case of problems with O2-bridges
pcmcia: fix unused function compile warning
pcmcia: vrc4173_cardu: Fix error path for pci_release_regions and pci_disable_device
pcmcia: add a few debug statements
pcmcia: remove obsolete and wrong comments
pcmcia: avoid messages on module (un)loading
pcmcia: move driver name to struct pcmcia_driver
pcmcia: remove the "Finally, report what we've done" message
pcmcia: use autoconfiguration feature for ioports and iomem
pcmcia: introduce autoconfiguration feature
pcmcia: Documentation update
pcmcia: convert pcmcia_request_configuration to pcmcia_enable_device
pcmcia: move config_{base,index,regs} to struct pcmcia_device
pcmcia: simplify IntType
pcmcia: simplify Status, ExtStatus register access
pcmcia: remove Pin, Copy configuration register access
pcmcia: move Vpp setup to struct pcmcia_device
... -
…/git/tip/linux-2.6-tip
* 'x86-amd-nb-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, amd_nb: Enable GART support for AMD family 0x15 CPUs
x86, amd: Use compute unit information to determine thread siblings
x86, amd: Extract compute unit information for AMD CPUs
x86, amd: Add support for CPUID topology extension of AMD CPUs
x86, nmi: Support NMI watchdog on newer AMD CPU families
x86, mtrr: Assume SYS_CFG[Tom2ForceMemTypeWB] exists on all future AMD CPUs
x86, k8: Rename k8.[ch] to amd_nb.[ch] and CONFIG_K8_NB to CONFIG_AMD_NB
x86, k8-gart: Decouple handling of garts and northbridges
x86, cacheinfo: Fix dependency of AMD L3 CID
x86, kvm: add new AMD SVM feature bits
x86, cpu: Fix allowed CPUID bits for KVM guests
x86, cpu: Update AMD CPUID feature bits
x86, cpu: Fix renamed, not-yet-shipping AMD CPUID feature bit
x86, AMD: Remove needless CPU family check (for L3 cache info)
x86, tsc: Remove CPU frequency calibration on AMD -
…/git/tip/linux-2.6-tip
* 'core-iommu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86/amd-iommu: Update copyright headers
x86/amd-iommu: Reenable AMD IOMMU if it's mysteriously vanished over suspend
AGP: Warn when GATT memory cannot be set to UC
x86, GART: Disable GART table walk probes
x86, GART: Remove superfluous AMD64_GARTEN -
…s/security-testing-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6: (26 commits)
selinux: include vmalloc.h for vmalloc_user
secmark: fix config problem when CONFIG_NF_CONNTRACK_SECMARK is not set
selinux: implement mmap on /selinux/policy
SELinux: allow userspace to read policy back out of the kernel
SELinux: drop useless (and incorrect) AVTAB_MAX_SIZE
SELinux: deterministic ordering of range transition rules
kernel: roundup should only reference arguments once
kernel: rounddown helper function
secmark: export secctx, drop secmark in procfs
conntrack: export lsm context rather than internal secid via netlink
security: secid_to_secctx returns len when data is NULL
secmark: make secmark object handling generic
secmark: do not return early if there was no error
AppArmor: Ensure the size of the copy is < the buffer allocated to hold it
TOMOYO: Print URL information before panic().
security: remove unused parameter from security_task_setscheduler()
tpm: change 'tpm_suspend_pcr' to be module parameter
selinux: fix up style problem on /selinux/status
selinux: change to new flag variable
selinux: really fix dependency causing parallel compile failure.
...
21 Oct, 2010
14 commits
-
Structure new_line is copied to userland with some padding fields unitialized.
It leads to leaking of stack memory.Signed-off-by: Vasiliy Kulikov
CC: stable@kernel.org
Signed-off-by: Dominik Brodowski -
The ports are char devices; do not have seeking capabilities. Calling
nonseekable_open() from the fops_open() call and setting the llseek fops
pointer to no_llseek ensures an lseek() call from userspace returns
-ESPIPE.Signed-off-by: Amit Shah
CC: Arnd Bergmann
Signed-off-by: Rusty Russell -
If a port has registered for SIGIO signals, let the application
know that the port is getting unplugged.Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell -
Send a SIGIO signal when new data arrives on a port. This is sent only
when the process has requested for the signal to be sent using fcntl().Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell -
A process can request for SIGIO on host connect / disconnect events
using the O_ASYNC file flag using fcntl().If that's requested, and if the guest-side connection for the port is
open, any host-side open/close events for that port will raise a SIGIO.
The process can then use poll() within the signal handler to find out
which port triggered the signal.Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell -
Explain in a comment why there's no need to reference-count the portdev
struct: when a device is yanked out, we can't do anything more with it
anyway so just give up doing anything more with the data or the vqs and
exit cleanly.Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell -
When a port got hot-unplugged, when a port was open, any file operation
after the unplugging resulted in a crash. This is fixed by ref-counting
the port structure, and releasing it only when the file is closed.This splits the unplug operation in two parts: first marks the port
as unavailable, removes all the buffers in the vqs and removes the port
from the per-device list of ports. The second stage, invoked when all
references drop to zero, releases the chardev and frees all other memory.Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell -
This moves to using cdev on the heap instead of it being embedded in the
ports struct. This helps individual refcounting and will allow us to
properly remove cdev structs after hot-unplugs and close operations.Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell -
To convert to using cdev as a pointer to avoid kref troubles, we have to
use a different method to get to a port from an inode than the current
container_of method.Add find_port_by_devt() that looks up all portdevs and ports with those
portdevs to find the right port.Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell -
The virtio_console.c driver is capable of handling multiple devices at a
time. Maintain a list of devices for future traversal.Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell -
Just re-arrange code for future patches.
Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell -
When a port is removed, we have to assume the port is gone. So a
success/failure return value doesn't make sense.Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell -
When a port is hot-unplugged while an app was blocked on a write() call,
the call was unblocked but would not get an error returned.Return -ENODEV to ensure the app knows the port has gone away.
Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell -
When a port is hot-unplugged while an app was blocked on a read() call,
the call was unblocked but would not get an error returned.Return -ENODEV to ensure the app knows the port has gone away.
Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell
