Calling transport_generic_request_failure() from here causes list
corruption. We should be using target_complete_cmd() instead.
Which we do in all other cases, so the UNKNOWN_OP case can become just
another member of the big else/if chain in tcmu_handle_completion().
Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Pull SCSI target updates from Nicholas Bellinger:
"It's been a busy development cycle for target-core in a number of
different areas.
The fabric API usage for se_node_acl allocation is now within
target-core code, dropping the external API callers for all fabric
drivers tree-wide.
There is a new conversion to RCU hlists for se_node_acl and
se_portal_group LUN mappings, that turns fast-past LUN lookup into a
completely lockless code-path. It also removes the original
hard-coded limitation of 256 LUNs per fabric endpoint.
The configfs attributes for backends can now be shared between core
and driver code, allowing existing drivers to use common code while
still allowing flexibility for new backend provided attributes.
The highlights include:
- Merge sbc_verify_dif_* into common code (sagi)
- Remove iscsi-target support for obsolete IFMarker/OFMarker
(Christophe Vu-Brugier)
- Add bidi support in target/user backend (ilias + vangelis + agover)
- Move se_node_acl allocation into target-core code (hch)
- Add crc_t10dif_update common helper (akinobu + mkp)
- Handle target-core odd SGL mapping for data transfer memory
(akinobu)
- Move transport ID handling into target-core (hch)
- Move task tag into struct se_cmd + support 64-bit tags (bart)
- Convert se_node_acl->device_list[] to RCU hlist (nab + hch +
paulmck)
- Convert se_portal_group->tpg_lun_list[] to RCU hlist (nab + hch +
paulmck)
- Simplify target backend driver registration (hch)
- Consolidate + simplify target backend attribute implementations
(hch + nab)
- Subsume se_port + t10_alua_tg_pt_gp_member into se_lun (hch)
- Drop lun_sep_lock for se_lun->lun_se_dev RCU usage (hch + nab)
- Drop unnecessary core_tpg_register TFO parameter (nab)
- Use 64-bit LUNs tree-wide (hannes)
- Drop left-over TARGET_MAX_LUNS_PER_TRANSPORT limit (hannes)"
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (76 commits)
target: Bump core version to v5.0
target: remove target_core_configfs.h
target: remove unused TARGET_CORE_CONFIG_ROOT define
target: consolidate version defines
target: implement WRITE_SAME with UNMAP bit using ->execute_unmap
target: simplify UNMAP handling
target: replace se_cmd->execute_rw with a protocol_data field
target/user: Fix inconsistent kmap_atomic/kunmap_atomic
target: Send UA when changing LUN inventory
target: Send UA upon LUN RESET tmr completion
target: Send UA on ALUA target port group change
target: Convert se_lun->lun_deve_lock to normal spinlock
target: use 'se_dev_entry' when allocating UAs
target: Remove 'ua_nacl' pointer from se_ua structure
target_core_alua: Correct UA handling when switching states
xen-scsiback: Fix compile warning for 64-bit LUN
target: Remove TARGET_MAX_LUNS_PER_TRANSPORT
target: use 64-bit LUNs
target: Drop duplicate + unused se_dev_check_wce
target: Drop unnecessary core_tpg_register TFO parameter
...
Pull networking updates from David Miller:
1) Add TX fast path in mac80211, from Johannes Berg.
2) Add TSO/GRO support to ibmveth, from Thomas Falcon
3) Move away from cached routes in ipv6, just like ipv4, from Martin
KaFai Lau.
4) Lots of new rhashtable tests, from Thomas Graf.
5) Run ingress qdisc lockless, from Alexei Starovoitov.
6) Allow servers to fetch TCP packet headers for SYN packets of new
connections, for fingerprinting. From Eric Dumazet.
7) Add mode parameter to pktgen, for testing receive. From Alexei
Starovoitov.
8) Cache access optimizations via simplifications of build_skb(), from
Alexander Duyck.
9) Move page frag allocator under mm/, also from Alexander.
10) Add xmit_more support to hv_netvsc, from KY Srinivasan.
11) Add a counter guard in case we try to perform endless reclassify
loops in the packet scheduler.
12) Extern flow dissector to be programmable and use it in new "Flower"
classifier. From Jiri Pirko.
13) AF_PACKET fanout rollover fixes, performance improvements, and new
statistics. From Willem de Bruijn.
14) Add netdev driver for GENEVE tunnels, from John W Linville.
15) Add ingress netfilter hooks and filtering, from Pablo Neira Ayuso.
16) Fix handling of epoll edge triggers in TCP, from Eric Dumazet.
17) Add an ECN retry fallback for the initial TCP handshake, from Daniel
Borkmann.
18) Add tail call support to BPF, from Alexei Starovoitov.
19) Add several pktgen helper scripts, from Jesper Dangaard Brouer.
20) Add zerocopy support to AF_UNIX, from Hannes Frederic Sowa.
21) Favor even port numbers for allocation to connect() requests, and
odd port numbers for bind(0), in an effort to help avoid
ip_local_port_range exhaustion. From Eric Dumazet.
22) Add Cavium ThunderX driver, from Sunil Goutham.
23) Allow bpf programs to access skb_iif and dev->ifindex SKB metadata,
from Alexei Starovoitov.
24) Add support for T6 chips in cxgb4vf driver, from Hariprasad Shenai.
25) Double TCP Small Queues default to 256K to accomodate situations
like the XEN driver and wireless aggregation. From Wei Liu.
26) Add more entropy inputs to flow dissector, from Tom Herbert.
27) Add CDG congestion control algorithm to TCP, from Kenneth Klette
Jonassen.
28) Convert ipset over to RCU locking, from Jozsef Kadlecsik.
29) Track and act upon link status of ipv4 route nexthops, from Andy
Gospodarek.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1670 commits)
bridge: vlan: flush the dynamically learned entries on port vlan delete
bridge: multicast: add a comment to br_port_state_selection about blocking state
net: inet_diag: export IPV6_V6ONLY sockopt
stmmac: troubleshoot unexpected bits in des0 & des1
net: ipv4 sysctl option to ignore routes when nexthop link is down
net: track link-status of ipv4 nexthops
net: switchdev: ignore unsupported bridge flags
net: Cavium: Fix MAC address setting in shutdown state
drivers: net: xgene: fix for ACPI support without ACPI
ip: report the original address of ICMP messages
net/mlx5e: Prefetch skb data on RX
net/mlx5e: Pop cq outside mlx5e_get_cqe
net/mlx5e: Remove mlx5e_cq.sqrq back-pointer
net/mlx5e: Remove extra spaces
net/mlx5e: Avoid TX CQE generation if more xmit packets expected
net/mlx5e: Avoid redundant dev_kfree_skb() upon NOP completion
net/mlx5e: Remove re-assignment of wq type in mlx5e_enable_rq()
net/mlx5e: Use skb_shinfo(skb)->gso_segs rather than counting them
net/mlx5e: Static mapping of netdev priv resources to/from netdev TX queues
net/mlx4_en: Use HW counters for rx/tx bytes/packets in PF device
...
This is the usual grab bag of driver updates (lpfc, hpsa,
megaraid_sas, cxgbi, be2iscsi) plus an assortment of minor updates.
There are also one new driver: the Cisco snic; the advansys driver has
been rewritten to get rid of the warning about converting it to the
DMA API, the tape statistics patch got in and finally, there's a
resuffle of SCSI header files to separate more cleanly initiator from
target mode (and better share the common definitions).
Signed-off-by: James Bottomley <JBottomley@Odin.com>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
iQEcBAABAgAGBQJViKWdAAoJEDeqqVYsXL0MAr8IAMmlA6HBVjMJJFCEOY9corHj
e70MNQa7LUgf+JCdOtzGcvHXTiFFd4IHZAwXUJAnsC4IU2QWEfi1bjUTErlqBIGk
LoZlXXpEHnFpmWot3OluOzzcGcxede8rVgPiKWVVdojIngBC2+LL/i2vPCJ84ri9
WCVlk6KBvWZXuU6JuOKAb2FO9HOX7Q61wuKAMast2Qc6RNc2ksgc7VbstsITqzZ9
FVEsjmQ5lqUj+xdxBpiUOdUpc22IJ4VcpBgQ2HrThvg6vf4aq937RJ/g4vi/g0SU
Utk0a3bUw1H/WnYAfJVFx83nVEsS/954Z7/ERDg1sjlfLYwQtQnpov0XIbPIbZU=
=k9IT
-----END PGP SIGNATURE-----
Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
Pull SCSI updates from James Bottomley:
"This is the usual grab bag of driver updates (lpfc, hpsa,
megaraid_sas, cxgbi, be2iscsi) plus an assortment of minor updates.
There is also one new driver: the Cisco snic. The advansys driver has
been rewritten to get rid of the warning about converting it to the
DMA API, the tape statistics patch got in and finally, there's a
resuffle of SCSI header files to separate more cleanly initiator from
target mode (and better share the common definitions)"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (156 commits)
snic: driver for Cisco SCSI HBA
qla2xxx: Fix indentation
qla2xxx: Comment out unreachable code
fusion: remove dead MTRR code
advansys: fix compilation errors and warnings when CONFIG_PCI is not set
mptsas: fix depth param in scsi_track_queue_full
megaraid: fix irq setup process regression
lpfc: Update version to 10.7.0.0 for upstream patch set.
lpfc: Fix to drop PLOGIs from fabric node till LOGO processing completes
lpfc: Fix scsi task management error message.
lpfc: Fix cq_id masking problem.
lpfc: Fix scsi prep dma buf error.
lpfc: Add support for using block multi-queue
lpfc: Devices are not discovered during takeaway/giveback testing
lpfc: Fix vport deletion failure.
lpfc: Check for active portpeerbeacon.
lpfc: Update driver version for upstream patch set 10.6.0.1.
lpfc: Change buffer pool empty message to miscellaneous category
lpfc: Fix incorrect log message reported for empty FCF record.
lpfc: Fix rport leak.
...
Pointers that are mapped by kmap_atomic() + offset must
be unmapped without the offset. That would cause problems
if the SG element length exceeds the PAGE_SIZE limit.
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Only include SCSI initiator header files in target code that needs
these header files, namely the SCSI pass-through code and the tcm_loop
driver. Change SCSI_SENSE_BUFFERSIZE into TRANSPORT_SENSE_BUFFER in
target code because the former is intended for initiator code and the
latter for target code. With this patch the only initiator include
directives in target code that remain are as follows:
$ git grep -nHE 'include .scsi/(scsi.h|scsi_host.h|scsi_device.h|scsi_cmnd.h)' drivers/target drivers/infiniband/ulp/{isert,srpt} drivers/usb/gadget/legacy/tcm_*.[ch] drivers/{vhost,xen} include/{target,trace/events/target.h}
drivers/target/loopback/tcm_loop.c:29:#include <scsi/scsi.h>
drivers/target/loopback/tcm_loop.c:31:#include <scsi/scsi_host.h>
drivers/target/loopback/tcm_loop.c:32:#include <scsi/scsi_device.h>
drivers/target/loopback/tcm_loop.c:33:#include <scsi/scsi_cmnd.h>
drivers/target/target_core_pscsi.c:39:#include <scsi/scsi_device.h>
drivers/target/target_core_pscsi.c:40:#include <scsi/scsi_host.h>
drivers/xen/xen-scsiback.c:52:#include <scsi/scsi_host.h> /* SG_ALL */
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
Conflicts:
drivers/net/phy/amd-xgbe-phy.c
drivers/net/wireless/iwlwifi/Kconfig
include/net/mac80211.h
iwlwifi/Kconfig and mac80211.h were both trivial overlapping
changes.
The drivers/net/phy/amd-xgbe-phy.c file got removed in 'net-next' and
the bug fix that happened on the 'net' side is already integrated
into the rest of the amd-xgbe driver.
Signed-off-by: David S. Miller <davem@davemloft.net>
With se_port and t10_alua_tg_pt_gp_member being absored into se_lun,
there is no need for an extra lock to protect se_lun->lun_se_dev
assignment.
This patch also converts backend drivers to use call_rcu() release
to allow any se_device readers to complete. The call_rcu() instead
of kfree_rcu() is required here because se_device is embedded into
the backend driver specific structure.
Also, convert se_lun->lun_stats to use atomic_long_t within the
target_complete_ok_work() completion callback, and add FIXME for
transport_lookup_tmr_lun() with se_lun->lun_ref.
Finally, update sbp_update_unit_directory() special case usage with
proper rcu_dereference_raw() and configfs symlink comment.
Reported-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Chris Boot <bootc@bootc.net>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Provide a common sets of dev_attrib attributes for all devices using the
generic SPC/SBC parsers, and a second one with the minimal required read-only
attributes for passthrough devices. The later is only used by pscsi for now,
but will be wired up for the full-passthrough TCMU use case as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Rewrite the backend driver registration based on what we did to the fabric
drivers: introduce a read-only struct target_bakckend_ops that the driver
registers, which is then instanciate as a struct target_backend by the
core. This allows the ops vector to be smaller and allows us to mark it
const. At the same time the registration function can set up the
configfs attributes, avoiding the need to add additional boilerplate code
for that to the drivers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Enable TCMU to handle bidirectional SCSI commands. In such cases,
entries in iov[] cover both the Data-In and the Data-Out buffers. The
first iov_cnt entries correspond to the Data-Out buffer, while the
remaining iov_bidi_cnt entries correspond to the Data-In buffer.
Signed-off-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
Signed-off-by: Vangelis Koukis <vkoukis@arrikto.com>
Reviewed-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Introduce alloc_and_scatter_data_area()/gather_and_free_data_area()
functions that allocate/deallocate space from the data area and copy
data to/from a given scatter-gather list. These functions are needed so
the next patch, introducing support for bidirectional commands in TCMU,
can use the same code path both for t_data_sg and for t_bidi_data_sg.
Signed-off-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
Signed-off-by: Vangelis Koukis <vkoukis@arrikto.com>
Reviewed-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Some SCSI commands (for example the TEST UNIT READY command) do not
carry data and so data_direction is DMA_NONE. Patch TCMU to not print a
warning message about unknown data direction, when it is DMA_NONE.
Signed-off-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
Signed-off-by: Vangelis Koukis <vkoukis@arrikto.com>
Reviewed-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
It seems like we only care if a transport is passthrough or not. Convert
transport_type to a flags field and replace TRANSPORT_PLUGIN_* with a
flag, TRANSPORT_FLAG_PASSTHROUGH.
Signed-off-by: Andy Grover <agrover@redhat.com>
Reviewed-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Aside from whether they handle BIDI ops or not, parsing of the CDB by
kernel and user SCSI passthrough modules should be identical. Move this
into a new passthrough_parse_cdb() and call it from tcm-pscsi and tcm-user.
Reported-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
After much discussion, give up on only passing a subset of SCSI commands
to userspace and pass them all. Based on what pscsi is doing, make sure
to set SCF_SCSI_DATA_CDB for I/O ops, and define attributes identical to
pscsi.
Make hw_block_size configurable via dev param.
Remove mention of command filtering from tcmu-design.txt.
Signed-off-by: Andy Grover <agrover@redhat.com>
Reviewed-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
All of these files were only building on non-x86 because of
the indirect of inclusion of vmalloc.h by, of all things,
"net/inet_hashtables.h"
None of this got caught during build testing, because on x86
there is an implicit vmalloc.h include via on of the arch asm/
headers.
This fixes all of these
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
TCMU requires more work to correctly handle both user handlers that want
all SCSI commands (pass_level=0) for a se_device, and also handlers that
just want I/O commands and let the others be emulated by the kernel
(pass_level=1). Only support the latter for now.
For full passthrough, we will need to support a second se_subsystem_api
template, due to configfs attributes being different between the two modes.
Thus pass_level is extraneous, and we can remove it.
The ABI break for TCMU v2 is already applied for this release, so it's
best to do this now to avoid another ABI break in the future.
Signed-off-by: Andy Grover <agrover@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
The initial version of TCMU (in 3.18) does not properly handle
bidirectional SCSI commands -- those with both an in and out buffer. In
looking to fix this it also became clear that TCMU's support for adding
new types of entries (opcodes) to the command ring was broken. We need
to fix this now, so that future issues can be handled properly by adding
new opcodes.
We make the most of this ABI break by enabling bidi cmd handling within
TCMP_OP_CMD opcode. Add an iov_bidi_cnt field to tcmu_cmd_entry.req.
This enables TCMU to describe bidi commands, but further kernel work is
needed for full bidi support.
Enlarge tcmu_cmd_entry_hdr by 32 bits by pulling in cmd_id and __pad1. Turn
__pad1 into two 8 bit flags fields, for kernel-set and userspace-set flags,
"kflags" and "uflags" respectively.
Update version fields so userspace can tell the interface is changed.
Update tcmu-design.txt with details of how new stuff works:
- Specify an additional requirement for userspace to set UNKNOWN_OP
(bit 0) in hdr.uflags for unknown/unhandled opcodes.
- Define how Data-In and Data-Out fields are described in req.iov[]
Changed in v2:
- Change name of SKIPPED bit to UNKNOWN bit
- PAD op does not set the bit any more
- Change len_op helper functions to take just len_op, not the whole struct
- Change version to 2 in missed spots, and use defines
- Add 16 unused bytes to cmd_entry.req, in case additional SAM cmd
parameters need to be included
- Add iov_dif_cnt field to specify buffers used for DIF info in iov[]
- Rearrange fields to naturally align cdb_off
- Handle if userspace sets UNKNOWN_OP by indicating failure of the cmd
- Wrap some overly long UPDATE_HEAD lines
(Add missing req.iov_bidi_cnt + req.iov_dif_cnt zeroing - Ilias)
Signed-off-by: Andy Grover <agrover@redhat.com>
Reviewed-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Contrary to common expectations for an "int" return, these functions
return only a positive value -- if used correctly they cannot even
return 0 because the message header will necessarily be in the skb.
This makes the very common pattern of
if (genlmsg_end(...) < 0) { ... }
be a whole bunch of dead code. Many places also simply do
return nlmsg_end(...);
and the caller is expected to deal with it.
This also commonly (at least for me) causes errors, because it is very
common to write
if (my_function(...))
/* error condition */
and if my_function() does "return nlmsg_end()" this is of course wrong.
Additionally, there's not a single place in the kernel that actually
needs the message length returned, and if anyone needs it later then
it'll be very easy to just use skb->len there.
Remove this, and make the functions void. This removes a bunch of dead
code as described above. The patch adds lines because I did
- return nlmsg_end(...);
+ nlmsg_end(...);
+ return 0;
I could have preserved all the function's return values by returning
skb->len, but instead I've audited all the places calling the affected
functions and found that none cared. A few places actually compared
the return value with <= 0 in dump functionality, but that could just
be changed to < 0 with no change in behaviour, so I opted for the more
efficient version.
One instance of the error I've made numerous times now is also present
in net/phonet/pn_netlink.c in the route_dumpit() function - it didn't
check for <0 or <=0 and thus broke out of the loop every single time.
I've preserved this since it will (I think) have caused the messages to
userspace to be formatted differently with just a single message for
every SKB returned to userspace. It's possible that this isn't needed
for the tools that actually use this, but I don't even know what they
are so couldn't test that changing this behaviour would be acceptable.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Now that fabric_max_sectors is no longer used to enforce the maximum
I/O size, go ahead and drop it's left-over usage in target-core and
associated backend drivers.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This patch converts TCM-USER to use an external set of device attributes,
and utilizes target_core_backend_configfs.h macros to generate a default
set of configfs extended-attr handlers.
It calls target_core_setup_sub_cits() to setup the initial config_item_type
based on existing target_core_configfs.c defaults, and using configfs_attribute
generated by DEF_TB_DEFAULT_ATTRIBS(tcmu) populates tcmu_backend_dev_attrs[]
It introduces no function change for existing TCMU device attributes.
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
If more than one thread is waiting for command ring space that includes
a PAD, then if the first one finishes (inserts a PAD and a CMD at the
start of the cmd ring) then the second one will incorrectly think it still
needs to insert a PAD (i.e. cmdr_space_needed is now wrong.) This will
lead to it asking for more space than it actually needs, and then inserting
a PAD somewhere else than at the end -- not what we want.
This patch moves the pad calculation inside is_ring_space_available() so
in the above scenario the second thread would then ask for space not
including a PAD. The patch also inserts a PAD op based upon an up-to-date
cmd_head, instead of the potentially stale value.
Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This patch fixes up the following unused return smatch warnings:
drivers/target/target_core_user.c:778 tcmu_netlink_event warn: unused return: ret = nla_put_string()
drivers/target/target_core_user.c:780 tcmu_netlink_event warn: unused `return: ret = nla_put_u32()
(Fix up missing semicolon: grover)
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Add a LIO storage engine that presents commands to userspace for execution.
This would allow more complex backstores to be implemented out-of-kernel,
and also make experimentation a-la FUSE (but at the SCSI level -- "SUSE"?)
possible.
It uses a mmap()able UIO device per LUN to share a command ring and data
area. The commands are raw SCSI CDBs and iovs for in/out data. The command
ring is also reused for returning scsi command status and optional sense
data.
This implementation is based on Shaohua Li's earlier version but heavily
modified. Differences include:
* Shared memory allocated by kernel, not locked-down user pages
* Single ring for command request and response
* Offsets instead of embedded pointers
* Generic SCSI CDB passthrough instead of per-cmd specialization in ring
format.
* Uses UIO device instead of anon_file passed in mailbox.
* Optional in-kernel handling of some commands.
The main reason for these differences is to permit greater resiliency
if the user process dies or hangs.
Things not yet implemented (on purpose):
* Zero copy. The data area is flexible enough to allow page flipping or
backend-allocated pages to be used by fabrics, but it's not clear these
are performance wins. Can come later.
* Out-of-order command completion by userspace. Possible to add by just
allowing userspace to change cmd_id in rsp cmd entries, but currently
not supported.
* No locks between kernel cmd submission and completion routines. Sounds
like it's possible, but this can come later.
* Sparse allocation of mmaped area. Current code vmallocs the whole thing.
If the mapped area was larger and not fully mapped then the driver would
have more freedom to change cmd and data area sizes based on demand.
Current code open issues:
* The use of idrs may be overkill -- we maybe can replace them with a
simple counter to generate cmd_ids, and a hash table to get a cmd_id's
associated pointer.
* Use of a free-running counter for cmd ring instead of explicit modulo
math. This would require power-of-2 cmd ring size.
(Add kconfig depends NET - Randy)
Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
David Disseldorp
Andy Grover
Linus Torvalds
Sagi Grimberg
Bart Van Assche
David S. Miller
Nicholas Bellinger
Christoph Hellwig
Ilias Tsitsimpis
Johannes Berg