The XATTR_ITEM is a type of a directory item so we use the common
validator helper. Unlike other dir items, it can have data. The way the
name len validation is currently implemented does not reflect that. We'd
have to adjust by the data_len when comparing the read and item limits.
However, this will not work for multi-item xattr dir items.
Example from tree dump of generic/337:
item 7 key (257 XATTR_ITEM 751495445) itemoff 15667 itemsize 147
location key (0 UNKNOWN.0 0) type XATTR
transid 8 data_len 3 name_len 11
name: user.foobar
data 123
location key (0 UNKNOWN.0 0) type XATTR
transid 8 data_len 6 name_len 13
name: user.WvG1c1Td
data qwerty
location key (0 UNKNOWN.0 0) type XATTR
transid 8 data_len 5 name_len 19
name: user.J3__T_Km3dVsW_
data hello
At the point of btrfs_is_name_len_valid call we don't have access to the
data_len value of the 2nd and 3rd sub-item. So simple btrfs_dir_data_len(leaf,
di) would always return 3, although we'd need to get 6 and 5 respectively to
get the claculations right. (read_end + name_len + data_len vs item_end)
We'd have to also pass data_len externally, which is not point of the
name validation. The last check is supposed to test if there's at least
one dir item space after the one we're processing. I don't think this is
particularly useful, validation of the next item would catch that too.
So the check is removed and we don't weaken the validation. Now tests
btrfs/048, btrfs/053, generic/273 and generic/337 pass.
Signed-off-by: David Sterba <dsterba@suse.com>
The newest devices need a longer time to reset because of
their more complex hardware. Wait 5ms after device reset.
Consolidate all the places that reset the device in the
PCIe transport to avoid future bugs.
While at it, unify the flow to use set_bit instead of full
write as requested by the hardware designers.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
iwl_pcie_apm_init can fail so make sure that the caller
takes the status into account.
Also, ensure that the error that iwl_pcie_apm_init can emit
will appear in the kernel log by default.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
When a station that's not associated sends a data frame (e.g. an NDP)
hostapd will respond with a disassoc frame, telling it that it's not
associated. The station might also not be authenticated, in which case
there will not be a station entry for it, and as a result we need to
accept such frames without a station.
Fixes: 3ee0f0e23e ("iwlwifi: mvm: fix DQA AP mode station assumption")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
When we get a non-STA frame to transmit in client mode, we try to use
the IWL_MVM_DQA_BSS_CLIENT_QUEUE queue (queue #4). However, at this
point, the queue might not be allocated at all, causing warnings. The
scenario on which this happened was a race condition between mac80211
and our queue allocation work:
* mac80211 sends auth
* we stop mac80211 queues to allocate a hw queue
* authentication is aborted
* we allocate HW queue and start mac80211 queues
* mac80211 removes station
* mac80211 hands us the auth frame from the pending queue
At this point, since mac80211 has already removed the station, we try
to transmit the frame through this special non-station case on queue
4 anyway.
In order to really use it properly, we'd have to again go through the
hw queue allocation work, and attach it to a station, etc. In this
case that isn't possible (there's no station anymore), but if this
special case were needed, then we'd have to do it this way.
However, the special case is documented to exist for TDLS, but can't
trigger there because the TDLS setup frames etc. are normal to-DS
frames going to the peer through the AP. Testing also confirms that
this code path isn't triggered in TDLS.
Therefore, remove the code path to avoid using an unused queue. The
erroneous frame described above will still be transmitted on the AUX
queue, but arguably that's a mac80211 problem, which will eventually
be fixed by moving everything there to TXQs.
Fixes: e3118ad74d ("iwlwifi: mvm: support tdls in dqa mode")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
When we get large sends on non-QoS association, we had a
bug that mangled the SNAP header. Fix that.
Fixes: a6d5e32f24 ("iwlwifi: mvm: send large SKBs to the transport")
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
When going into suspend, the HW configuration for MSI-X will
likely be lost. As a consequence, after waking up, all IRQ
causes will be mapped to interrupt 0, and as a consequence we
don't notice the interrupt because in most cases this is an
interrupt for a queue, and getting it doesn't read the other
cause registers.
Fixes: 2e5d4a8f61 ("iwlwifi: pcie: Add new configuration to enable MSIX")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Getting the TID of a packet before we know it is a QoS data
packet isn't a good idea. Delay the TID retrieval until
we know the packet is a QoS data packet.
Fixes: bb81bb68f4 ("iwlwifi: mvm: add Tx A-MSDU inside A-MPDU")
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
When in non-DQA mode, mac80211 actually gets a pretty much perfect
idea (in vif->hw_queue/cab_queue) of which queues we're using. But
in DQA mode, this isn't true - nonetheless, we were adding all the
queues, even the ones stations are using, to the queue allocation
bitmap.
Fix this, we should only add the queues we really are using in DQA
mode:
* IWL_MVM_OFFCHANNEL_QUEUE, as we use this in both modes
* mvm->aux_queue, as we use this in both modes - mac80211
never really knows about it but we use it as a cookie
internally, so can't reuse it
* possibly the GCAST queue (cab_queue)
* all the "queues" we told mac80211 about we were using on each
interface (vif->hw_queue), these are entirely virtual in this
mode
Also add back the failure now when we can't allocate any more of
these - now virtual - queues; this was skipped in DQA mode and
would lead to having multiple ACs or even interfaces use the same
queue number in mac80211 (10, since that's the limit), which would
stop far too many queues if stopped.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
There may be a difference between the mac80211 vif->cab_queue and
mvmvif->cab_queue, particularly with TVQM. Make the code map this
earlier, instead of first returning the mac80211 one again from
iwl_mvm_get_ctrl_vif_queue().
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
In the driver, we track which hardware queue is associated with
which mac80211 "hw_queue", in order to be able to stop and wake
it. When moving these bitmaps out of the queue_info structures,
the type of the bitmap was erroneously changed from u32 to u8,
presumably in order to save memory.
Turns out that u32 isn't needed, because the highest queue we
can ever tell mac80211 is always < 16, but a u16 definitely is
needed, queues >=8 do happen.
While at it, throw a BUILD_BUG_ON() into the place where we set
the limit (mvm->first_agg_queue) and a warning when it actually
gets put into the bitmap.
The consequence of this bug is that full HW queues associated
with such a too-high mac80211 number never stop higher layer
queues when full, and thus would simply drop all packets that
couldn't be enqueued to the hardware queue.
Fixes: 34e10860ae ("iwlwifi: mvm: remove references to queue_info in new TX path")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
The code was intended to enable IP header checksumming on AMSDUs, but
failed to really do so because the A-MSDU bit was set after all the
checksumming bits, and thus checking for A-MSDU could never be true.
Fix this by setting the A-MSDU bit before the offload bits.
Fixes: 5e6a98dc48 ("iwlwifi: mvm: enable TCP/UDP checksum support for 9000 family")
Reported-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
We have tracing for both pre-ICT and ICT interrupts, including all
the data read there. Extend the tracing to MSI-X interrupts.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Martin KaFai Lau says:
====================
bpf: Add syscall lookup support for fd array and htab
This patchset adds BPF_MAP_LOOKUP_ELEM syscall support for
BPF_MAP_TYPE_PROG_ARRAY,
BPF_MAP_TYPE_ARRAY_OF_MAPS and
BPF_MAP_TYPE_HASH_OF_MAPS
====================
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Checks are added to the existing sockex3 and test_map_in_map test.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch allows userspace to do BPF_MAP_LOOKUP_ELEM on
BPF_MAP_TYPE_PROG_ARRAY,
BPF_MAP_TYPE_ARRAY_OF_MAPS and
BPF_MAP_TYPE_HASH_OF_MAPS.
The lookup returns a prog-id or map-id to the userspace.
The userspace can then use the BPF_PROG_GET_FD_BY_ID
or BPF_MAP_GET_FD_BY_ID to get a fd.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
In case a VLAN device is enslaved to a bridge we shouldn't create a
router interface (RIF) for it when it's configured with an IP address.
This is already handled by the driver for other types of netdevs, such
as physical ports and LAG devices.
If this IP address is then removed and the interface is subsequently
unlinked from the bridge, a NULL pointer dereference can happen, as the
original 802.1d FID was replaced with an rFID which was then deleted.
To reproduce:
$ ip link set dev enp3s0np9 up
$ ip link add name enp3s0np9.111 link enp3s0np9 type vlan id 111
$ ip link set dev enp3s0np9.111 up
$ ip link add name br0 type bridge
$ ip link set dev br0 up
$ ip link set enp3s0np9.111 master br0
$ ip address add dev enp3s0np9.111 192.168.0.1/24
$ ip address del dev enp3s0np9.111 192.168.0.1/24
$ ip link set dev enp3s0np9.111 nomaster
Fixes: 99724c18fc ("mlxsw: spectrum: Introduce support for router interfaces")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Petr Machata <petrm@mellanox.com>
Tested-by: Petr Machata <petrm@mellanox.com>
Reviewed-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When qdisc fail to init, qdisc_create would invoke the destroy callback
to cleanup. But there is no check if the callback exists really. So it
would cause the panic if there is no real destroy callback like the qdisc
codel, fq, and so on.
Take codel as an example following:
When a malicious user constructs one invalid netlink msg, it would cause
codel_init->codel_change->nla_parse_nested failed.
Then kernel would invoke the destroy callback directly but qdisc codel
doesn't define one. It causes one panic as a result.
Now add one the check for destroy to avoid the possible panic.
Fixes: 87b60cfacf ("net_sched: fix error recovery at qdisc creation")
Signed-off-by: Gao Feng <gfree.wind@vip.163.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We don't hold any tx lock when trying to disable TX during reset, this
would lead a use after free since ndo_start_xmit() tries to access
the virtqueue which has already been freed. Fix this by using
netif_tx_disable() before freeing the vqs, this could make sure no tx
after vq freeing.
Reported-by: Jean-Philippe Menil <jpmenil@gmail.com>
Tested-by: Jean-Philippe Menil <jpmenil@gmail.com>
Fixes commit f600b69050 ("virtio_net: Add XDP support")
Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Robert McCabe <robert.mccabe@rockwellcollins.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Version 3.70a of the Designware has additional DMA registers so
add those to the ethtool DMA Register dump.
Offset 9 - Receive Interrupt Watchdog Timer Register
Offset 10 - AXI Bus Mode Register
Offset 11 - AHB or AXI Status Register
Offset 22 - HW Feature Register
Signed-off-by: Thor Thayer <thor.thayer@linux.intel.com>
Acked-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
"struct nf_loginfo li;" is a local variable, so we should set the flags
to 0 explicitly, else, packets maybe truncated unexpectedly when copied
to the userspace.
Fixes: 7643507fe8 ("netfilter: xt_NFLOG: nflog-range does not truncate packets")
Cc: Vishwanath Pai <vpai@akamai.com>
Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Now that compat_vfp_get() uses the regset API to copy the FPSCR
value out to userspace, compat_vfp_set() looks inconsistent. In
particular, compat_vfp_set() will fail if called with kbuf != NULL
&& ubuf == NULL (which is valid usage according to the regset API).
This patch fixes compat_vfp_set() to use user_regset_copyin(),
similarly to compat_vfp_get().
This also squashes a sparse warning triggered by the cast that
drops __user when calling get_user().
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
compat_vfp_set() checks for userspace trying to write an excessive
amount of data to the regset. However this check is conspicuous
for its absence from every other _set() in the arm64 ptrace
implementation. In fact, the core ptrace_regset() already clamps
userspace's iov_len to the regset size before the individual regset
.{get,set}() methods get called.
This patch removes the redundant check.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
If get_user() fails when reading the new FPSCR value from userspace
in compat_vfp_get(), then garbage* will be written to the task's
FPSR and FPCR registers.
This patch prevents this by checking the return from get_user()
first.
[*] Actually, zero, due to the behaviour of get_user() on error, but
that's still not what userspace expects.
Fixes: 478fcb2cdb ("arm64: Debugging support")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Stats can be read from atomic context, hence make stats_lock as
a spinlock.
Fix the following trace with debug kernel.
BUG: sleeping function called from invalid context at
kernel/locking/mutex.c:238
in_atomic(): 1, irqs_disabled(): 0, pid: 6487, name: sadc
Call Trace:
dump_stack+0x63/0x90
___might_sleep+0xda/0x130
__might_sleep+0x4a/0x90
mutex_lock+0x20/0x50
opa_vnic_get_stats64+0x56/0x140 [opa_vnic]
dev_get_stats+0x74/0x130
dev_seq_printf_stats+0x37/0x120
dev_seq_show+0x14/0x30
seq_read+0x26d/0x3d0
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Pass GFP_ATOMIC flag to ib_create_send_mad() while sending trap as it
can be triggered from the atomic context.
Fix the following trace with debug kernel.
BUG: sleeping function called from invalid context at mm/slab.h:432
in_atomic(): 1, irqs_disabled(): 0, pid: 1771, name: NetworkManager
Call Trace:
dump_stack+0x63/0x90
___might_sleep+0xda/0x130
__might_sleep+0x4a/0x90
__kmalloc+0x19e/0x220
? ib_create_send_mad+0xea/0x390 [ib_core]
ib_create_send_mad+0xea/0x390 [ib_core]
opa_vnic_vema_send_trap+0x17b/0x460 [opa_vnic]
opa_vnic_vema_report_event+0x57/0x80 [opa_vnic]
opa_vnic_mac_send_event+0xaa/0xf0 [opa_vnic]
opa_vnic_set_rx_mode+0x17/0x30 [opa_vnic]
__dev_set_rx_mode+0x52/0x90
dev_set_rx_mode+0x26/0x40
__dev_open+0xe8/0x140
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
The debugfs interface has calls a function that was evidently
defined under the wrong name in some configurations:
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c:64:12: error: 'amdgpu_debugfs_test_ib_ring_init' used but never defined [-Werror]
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c:3803:12: error: 'amdgpu_debugfs_test_ib_init' defined but not used [-Werror=unused-function]
This fixes the function name.
Fixes: 4f0955fcc0 ("drm/amdgpu: export test ib debugfs interface")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
caused by not program dynamic_cu_mask_addr in the KIQ MQD.
v2: create struct vi_mqd_allocation in FB which will contain
1. PM4 MQD structure.
2. Write Pointer Poll Memory.
3. Read Pointer Report Memory
4. Dynamic CU Mask.
5. Dynamic RB Mask.
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Saeed Mahameed says:
====================
mlx5-updates-2017-06-27 (Innova IPsec offload support)
This patchset adds support for Innova IPSec network interface card.
About Innova device:
--------------------
Innova is a network card with a ConnectX chip and an FPGA chip as a
bump-on-the-wire.
Internal
+----------+ Link +-----------------+
| +--------------+ FPGA | +------+
| ConnectX | | Shell +--+ QSFP |
| +--------------+ +-------+ | | Port |
+----------+ I2C | | SBU | | +------+
| +-------+ |
+--+----------+---+
| |
+--+--+ +---+---+
| DDR | | Flash |
+-----+ +-------+
The FPGA synthesized logic is loaded from dedicated flash storage and has
access to its own dedicated DDR RAM.
The ConnectX chip firmware programs the FPGA by accessing its configuration
space over either the slow internal I2C link or the high-speed internal link.
The FPGA logic is divided into a "Shell" and a "Sandbox Unit" (SBU).
mlx5_core driver (with CONFIG_MLX5_FPGA) handles all shell functionality,
while other components may handle the various SBU functionalities.
The driver opens high-speed reliable communication channels with the shell and
the SBU over the internal link.
These channels may be used for high-bandwidth configuration or for SBU-specific
out-of-band data paths.
About Innova IPSec device:
--------------------------
Innova IPSec is a network card that allows offloading IPSec cryptography operations
from the host CPU to the NIC. It is an Innova card with an IPSec SBU.
The hardware keeps the database of IPSec Security Associations (SADB) in the FPGA's
DDR memory.
Internal
+----------+ Link +-----------------+
| +--------------+ FPGA | +------+
| ConnectX | | Shell +--+ QSFP |
| +--------------+ +-------+ | | Port |
+----------+ Internal I2C | | IPSec | | +------+
| | SBU | |
| +-------+ |
+--+----------+---+
| |
+--+--+ +---+---+
| DDR | | |
| | | Flash |
|SADB | | |
+-----+ +-------+
Modes and ciphers:
Currently the following modes and ciphers are supported:
IPv4 and IPv6
ESP tunnel and transport modes
AES 128 and 256 bit encryption, with GCM authentication (RFC4106)
IV is generated using seqiv, in sync with Linux's geniv.
More modes and ciphers may be added later.
Notes:
In the future similar functionality will be included in a single-chip NIC.
About the driver:
-----------------
Patches 1-4 prepare some existing driver code for the new feature:
* Add support for reserved GIDs in the hardware GID table
* Allow multiple modules to enable hardware RoCE support independently
Patches 5-6 define structs and helper functions for QP work-queues.
Patches 7-11 add various FPGA-related features required for Innova.
IPSec.
Patch 12 adds abstraction layer for Mellanox IPSec-offload capable devices.
atches 13-16 add IPSec offload support to the mlx5 netdevice.
This driver services the new IPSec offload API introduced in commit
d77e38e612 ("xfrm: Add an IPsec hardware offloading API")
Configuration Path:
If Innova IPSec device is detected, the mlx5e netdevice gets the new
NETIF_F_HW_ESP feature and the xdo callbacks, indicating ESP offload
capabilities, and also the matching TX checksum and GSO features.
The driver configures offloaded Security Associations (SAs) by sending
an ADD_SA or DEL_SA message to the IPSec SBU, which updates the SADB in DDR.
These messages and their responses are sent over a high-speed channel.
Counters for ethtool are retrieved by the driver from the SBU.
Data path:
On receive path, the SBU decrypts ESP packets which match the offloaded SADB,
but keeps them encapsulated.
The SBU injects metadata (Mellanox owned ethertype) indicating that crypto-offload
has taken place, the SA with which it was done, and the authentication result.
The ConnectX chip performs RX checksum offload on the packet, and RSS using the
ESP SPI value. The driver detects the special ethertype, and attaches a struct
secpath to the RX SKB, including flags to indicate that crypto offload took place,
the authentication result, and which xfrm_state was used for decryption, in the
olen and ovec members. The RX SKB may have useful CHECKSUM_COMPLETE. A separate
patchset will add support for that in the xfrm stack.
On transmit path, the stack encapsulates the packet but does not encrypt it, and
indicates in the SKB's secpath that crypto offload is to be performed and the SA
to use to do so.
The driver avoids performing crypto-offload for ESP fragments, and packets with
IP options, as the SBU cannot currently do that. For eligible packets, the driver
prepends a special ethertype with metadata instructing the hardware to perform crypto offload.
The stack builds regular (non-GSO) SKBs so that they contain a placeholder for the ESP trailer.
The driver trims it off, because the SBU automatically appends the trailer for offloaded packets.
The ConnectX chip performs TX checksum offload on inner UDP or TCP packets,
and GSO for TCP packets (duplicating the prepended metadata).
The segmented packets then undergo encryption in the SBU before going on the wire.
Performance:
We measure single stream of TCP on Intel(R) Xeon(R) CPU E5-2643 v2 @3.50GHz
Using AES-NI with ESP GSO we get constant 4.1 Gbps.
Using crypto offload we get constant 18 Gbps.
Note that these numbers require CHECKSUM_COMPLETE support in XFRM, which we submit separately.
- Ilan Tayari
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
The pmem driver attaches to both persistent and volatile memory ranges
advertised by the ACPI NFIT. When the region is volatile it is redundant
to spend cycles flushing caches at fsync(). Check if the hosting region
is volatile and do not set dax_write_cache() if it is.
Cc: Jan Kara <jack@suse.cz>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The dax_flush() operation can be turned into a nop on platforms where
firmware arranges for cpu caches to be flushed on a power-fail event.
The ACPI 6.2 specification defines a mechanism for the platform to
indicate this capability so the kernel can select the proper default.
However, for other platforms, the administrator must toggle this setting
manually.
Given this flush setting is a dax-specific mechanism we advertise it
through a 'dax' attribute group hanging off a host device. For example,
a 'pmem0' block-device gets a 'dax' sysfs-subdirectory with a
'write_cache' attribute to control response to dax cache flush requests.
This is similar to the 'queue/write_cache' attribute that appears under
block devices.
Cc: Jan Kara <jack@suse.cz>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
