The checking of Auto-Hibernation support is used in many places in the
driver, thus re-factor it as ufshcd_is_auto_hibern8_supported() to make
code more clean.
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: Avri Altman <Avri.Altman@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Since we are processing events synchronously now, the second call of
sas_ex_join_wide_port() in sas_ex_discover_dev() is not needed. There will
be no races with other works in disco workqueue. So remove the second
sas_ex_join_wide_port().
I did not change the return value of 'res' to error when discover failed
because we need to continue to discover other phys if one phy discover
failed. So let's keep that logic as before and just add a debug log to
detect the failure. And directly return if second fanout expander attatched
to the parent expander because it has nothing to do after the phy is
disabled.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Use *_pool_zalloc rather than *_pool_alloc followed by memset with 0.
Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Acked-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Currently the check for a lockup_detected failure exits via the label
return_reset_status that reads and dereferences an uninitialized pointer
dev. Fix this by ensuring dev is inintialized to null.
Addresses-Coverity: ("Uninitialized pointer read")
Fixes: 14991a5bade5 ("scsi: hpsa: correct device resets")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Don Brace <don.brace@microsemi.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Fix the following warning reported by coccicheck:
drivers/target/iscsi/iscsi_target_nego.c:175:6-8: WARNING: possible
condition with no effect (if == else)
Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
Reviewed-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Fix abord to abort.
Signed-off-by: Weitao Hou <houweitaoo@gmail.com>
Acked-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add PCMCIA card support to Future Domain SCSI driver.
Tested with IBM SCSI PCMCIA Adapter 40G1890.
Signed-off-by: Ondrej Zary <linux@zary.sk>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add register bit definitions from documentation to header file and use them
instead of magic constants. No changes to generated binary.
Signed-off-by: Ondrej Zary <linux@zary.sk>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
After a successful SRP login response we call scsi_unblock_requests() to
kick any pending IOs. The callback to process this SRP response happens in
a tasklet and therefore is in softirq context. The result of such is that
when blk-mq is enabled, it is no longer safe to call scsi_unblock_requests()
from this context. The result of duing so triggers the following WARN_ON
splat in dmesg after a host reset or CRQ reenablement.
WARNING: CPU: 0 PID: 0 at block/blk-mq.c:1375 __blk_mq_run_hw_queue+0x120/0x180
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.0.0-rc8 #4
NIP [c0000000009771e0] __blk_mq_run_hw_queue+0x120/0x180
LR [c000000000977484] __blk_mq_delay_run_hw_queue+0x244/0x250
Call Trace:
__blk_mq_delay_run_hw_queue+0x244/0x250
blk_mq_run_hw_queue+0x8c/0x1c0
blk_mq_run_hw_queues+0x60/0x90
scsi_run_queue+0x1e4/0x3b0
scsi_run_host_queues+0x48/0x80
login_rsp+0xb0/0x100
ibmvscsi_handle_crq+0x30c/0x3e0
ibmvscsi_task+0x54/0xe0
tasklet_action_common.isra.3+0xc4/0x1a0
__do_softirq+0x174/0x3f4
irq_exit+0xf0/0x120
__do_irq+0xb0/0x210
call_do_irq+0x14/0x24
do_IRQ+0x9c/0x130
hardware_interrupt_common+0x14c/0x150
This patch fixes the issue by introducing a new host action for unblocking
the scsi requests in our seperate work thread.
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
The current implemenation relies on two flags in the driver's private host
structure to signal the need for a host reset or to reenable the CRQ after
a LPAR migration. This patch does away with those flags and introduces a
single action flag and defined enums for the supported kthread work
actions. Lastly, the if/else logic is replaced with a switch statement.
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Wire up the host_reset function in our driver_template to allow a user
requested adpater reset via the host_reset sysfs attribute.
Example:
echo "adapter" > /sys/class/scsi_host/host0/host_reset
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Update lpfc version to 12.2.0.3
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Kernel warnings may be seen with preempt debugging enabled.
Replace smp_processor_id calls with raw_smp_processor_id or cpu information
stored in hdwq structures.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Crashes in scsi_queue_rq or in dma_unmap_direct_sg during BFS when lpfc has
lpfc_enable_bg=1.
lpfc is setting DIX and prot sg after scsi_add_host_with_dma() has been
called. The scsi_host_set_prot() and scsi_host_set_guard() routines need to
be called before scsi_add_host_with_dma().
Revise the calling sequence to set the protection/guard data before calling
scsi_add_host_with_dma().
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
FDMI protocol support registration was not accurately showing nvme
support. The fcponly-path clears the parameter object.
Move the code out of the fcponly code path. Fix the FDMI registration data
to properly check for nvme support. Commonize the manner in which the fdmi
routines set protocol support.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Issuing a LUN reset was resulting in a command failure which then escalated
to a host reset.
The FCP-4 spec allows fcp_rsp_len field to specify the number of valid
bytes of FCP_RSP_INFO, and the value could be 4 or 8. The driver is
allowing only a value of 8, thus it failed the command.
Revise the driver to allow 4 or 8.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
While fixing the resources per socket, realized the driver was not using
hardware queues (up to 1 per cpu) if there were fewer interrupt
vectors. The driver was only using the hardware queue assigned to the cpu
with the vector.
Rework the affinity map check to use the additional hardware queue elements
that had been allocated. If the cpu count exceeds the hardware queue count
- share, but choose what is shared with by: hyperthread peer, core peer,
socket peer, or finally similar cpu in a different socket.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
The driver was coded expecting enough hardware queues and interrupt vectors
such that at least there was one per socket. In the case where there were
fewer than sockets, cpus were left unassigned thus null pointers.
Rework the affinity mappings. Map settings for the cpu's that are in the
irq cpu mask. For each cpu not in the mask, map to another cpu that does
have a mask. Choice of the "other" cpu will attempt to map to the same cpu
but differing hyperthread, or cpu within in same core, or cpu within same
socket, or finally cpu in the base socket.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Invalid logical speed is displayed for trunk enabled ports when all ports
are down. Also noted that link speed is incorrectly reported for the units
when links are up.
Current code is returning the logical link speed from the last event from
the adapter. In cases where the last link went down, the link speed in the
event was not valid - meaning that although the links where down the field
had a bogus value.
Rework the event handling to qualify the trunk link state before using the
event speed data.
Also correct units on other areas where the logical link speed was taken
from a link event.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
eq create is leaking mailbox memory if it encounters an error.
rework error path to free the memory.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
The driver unconditionally says fw doesn't support nvme when in
truth it was a driver parameter settings that disabled nvme support.
Rework the code validating nvme support to accurately report what
condition is disabling nvme support. Save state on whether nvme
fw supports nvme in case sysfs attributes change dynamically.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
There is a race condition with the abort handler declaring a waitq
item on it's stack, followed by a timeout in the abort handler that
has it give up on the abort return to its caller. When the io is
finally aborted and its completion handler called, it references
the waitq element that the abort_handler set up, which is no longer
valid resulting in a deadlock.
Fix by clearing the waitq reference, under lock, when the abort
handler timeout gives up. Have the completion handler validate the
waitq before referencing it.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
When queued work is executed posting a new command to the transport
the driver is reporting a null buffer.
The driver had received an ABTS which matched a command that had
been scheduled for delivery to the transport. The driver proceeded
to cancel the command, but the work item was never cancelled.
Fix by cancelling the queued work item. Also turns out the ABTS
response was not properly sending a BA_ACC, so set the flag to
send the ACC.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Use-after-free memory overwrite detected. Problem reported
by Ewan Milne at Red Hat after running lpfc target with additional
memory checking enabled.
Race condition when lpfc_nvmet_xmt_ls_rsp_cmp frees the ctxp
memory in interrupt context before lpfc_nvmet_xmt_ls_rsp
clears a field in the ctxp after successfully issuing the wqe.
Remove the unnecessary ctxp write after reposting the rq buffer. The
ctxp->rqb_buffer field is not checked in LS handling after the wqe
is submitted.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reported-by: Ewan Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Under heavy load the target stops responding, the drivers aborts
timeout and we start recovery by logging out of the target, but
the target is never logged into again.
In a point-to-point scenario, there were battling PLOGI's. When we
received a PLOGI request after having sent one, the driver cancels
the processing of the original plogi. However, the completion path
of the remaining plogi was coded to skip the reg_rpi that should
be happening on the 2nd plogi.
Correct by adding a simple pt2pt check such that the 2nd plogi isn't
skipped and the reg_login occurs.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Turns out the message change in 12.2.0.1 for unsupported topology
makes the linux driver out of sync with other products.
Revert the message back to the prior content for product consistency.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
The driver currently is relying on firmware to match ABTSs to existing
exchanges. This works fine as long as an exchange has been assigned to the
io and work posted to it. However, for unmapped frames (rxid=0xFFFF), the
driver has yet to assign an xri. The driver was blindly saying it couldn't
match the ABTS and sending the BA_xxx. However, the command frame may have
been in queues waiting on xri's before posting to the nvmet_fc layer. When
xri's became available, the command frame would still be pushed to the
transport and that io would execute, even though the io had been killed by
ABTS. The initiator, seeing the io ABTS'd, would reuse the exchange for a
different io which would be received on the target and pushed up. If the
"zombie" io then came back down and started transmitting, the initiator
would match the oxid and accept erroneous data. Bad things happened.
Add tracking of active exchanges in the target to allow matching of a
received ABTS against active or pending IO requests. If the ABTS is matched
to a pending or active IO, the drive initiates cleanup and conditionally
notifies the transport.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Currently the driver is notified of new command frame receipt by CQEs. As
part of the CQE processing, the driver upcalls the nvmet_fc transport to
deliver the command. nvmet_fc, as part of receiving the command builds out
a context for it, where one of the first steps is to allocate memory for
the io.
When running with tests that do large ios (1MB), it was found on some
systems, the total number of outstanding I/O's, at 1MB per, completely
consumed the system's memory. Thus additional ios were getting blocked in
the memory allocator. Given that this blocked the lpfc thread processing
CQEs, there were lots of other commands that were received and which are
then held up, and given CQEs are serially processed, the aggregate delays
for an IO waiting behind the others became cummulative - enough so that the
initiator hit timeouts for the ios.
The basic fix is to avoid the direct upcall and instead schedule a work
item for each io as it is received. This allows the cq processing to
complete very quickly, and each io can then run or block on it's own.
However, this general solution hurts latency when there are few ios. As
such, implemented the fix such that the driver watches how many CQEs it has
processed sequentially in one run. As long as the count is below a
threshold, the direct nvmet_fc upcall will be made. Only when the count is
exceeded will it revert to work scheduling.
Given that debug of this showed a surprisingly long delay in cq processing,
the io timer stats were updated to better reflect the processing of the
different points.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Revise a stalled adapter message to also include the number of jobs that
are stalling the thread.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
A race condition resulted in receive buffers being placed in the free list
twice.
Change the locking and handling to check whether the "other" path will be
freeing the entry in a later thread and skip it if it is.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
After receiving an unsolicited ABTS (meaning rxid is 0xFFFF), the driver
used the oxid from the initiator to match against a local xri which may
have been allocated for the io. The xri would be the rxid - it's an invalid
check resulting in the command not being matched or erroneously matched.
Change the lookup to use the oxid and the SID to match against received
IO's original values.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Softlockups are seen in low memory situations. They are due to doing
oas_lun allocation with GFP_KERNEL in atomic contexts.
Change the calls to oas_lun to indicate atomic context so that GFP_ATOMIC
is used.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Create a debugfs interface for megaraid_sas driver. Provide interface to
dump driver RAID map in debugfs.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Print FW supported MSI-X vector count only if FW supports
MSI-X.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add debug prints related to device list being returned by firmware. The a
debug flag to activate these prints.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add prints in resume/suspend path to help in debugging hibernation
issues. The print gives an indication when the driver entry points are
called.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add a print to dump the interrupt status in system log for debugging.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
When driver detects a firmware fault during load, dump additional
information on fault code and subcode that will help in debugging.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add a sysfs interface to get the raid map index that is being used by
driver.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add prints for BAR address information during driver load. This helps in
debugging issues with BAR address changing during OS boot.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
When controller fails to transition to READY state during driver probe,
dump the system interface register set. This will give snapshot of the
firmware status for debugging driver load issues.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add a sysfs interface to dump the controller's system interface registers.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add option to format the buffer that is being dumped. Currently, the IO
frame and chain frame dumped in the syslog is getting split across multiple
lines based on the formatting. Fix this by using KERN_CONT in printk.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add prints to identify the internal DCMD opcode that has timed out.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This patch enhances the existing debug prints in reset and task management
path.
These debug prints in adapter reset path helps with debugging issues
related to IO timeouts that are seen frequently in the field. Add
additional debug prints to dump the pending command frames before
initiating an adapter reset. Also, print FastPath IOs that are
outstanding.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Driver will use "reply descriptor post queues" in round robin fashion when
the combined MSI-X mode is not enabled. With this IO completions are
distributed and load balanced across all the available reply descriptor
post queues equally.
This is enabled only if combined MSI-X mode is not enabled in firmware.
This improves performance and also fixes soft lockups.
When load balancing is enabled, IRQ affinity from driver needs to be
disabled.
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Issue Description:
We have seen cpu lock up issues from field if system has a large (more than
96) logical cpu count. SAS3.0 controller (Invader series) supports max 96
MSI-X vector and SAS3.5 product (Ventura) supports max 128 MSI-X vectors.
This may be a generic issue (if PCI device support completion on multiple
reply queues).
Let me explain it w.r.t megaraid_sas supported h/w just to simplify the
problem and possible changes to handle such issues. MegaRAID controller
supports multiple reply queues in completion path. Driver creates MSI-X
vectors for controller as "minimum of (FW supported Reply queues, Logical
CPUs)". If submitter is not interrupted via completion on same CPU, there
is a loop in the IO path. This behavior can cause hard/soft CPU lockups, IO
timeout, system sluggish etc.
Example - one CPU (e.g. CPU A) is busy submitting the IOs and another CPU
(e.g. CPU B) is busy with processing the corresponding IO's reply
descriptors from reply descriptor queue upon receiving the interrupts from
HBA. If CPU A is continuously pumping the IOs then always CPU B (which is
executing the ISR) will see the valid reply descriptors in the reply
descriptor queue and it will be continuously processing those reply
descriptor in a loop without quitting the ISR handler.
megaraid_sas driver will exit ISR handler if it finds unused reply
descriptor in the reply descriptor queue. Since CPU A will be continuously
sending the IOs, CPU B may always see a valid reply descriptor (posted by
HBA Firmware after processing the IO) in the reply descriptor queue. In
worst case, driver will not quit from this loop in the ISR handler.
Eventually, CPU lockup will be detected by watchdog.
Above mentioned behavior is not common if "rq_affinity" set to 2 or
affinity_hint is honored by irqbalancer as "exact". If rq_affinity is set
to 2, submitter will be always interrupted via completion on same CPU. If
irqbalancer is using "exact" policy, interrupt will be delivered to
submitter CPU.
Problem statement:
If CPU count to MSI-X vectors (reply descriptor Queues) count ratio is not
1:1, we still have exposure of issue explained above and for that we don't
have any solution.
Exposure of soft/hard lockup is seen if CPU count is more than MSI-X
supported by device.
If CPUs count to MSI-X vectors count ratio is not 1:1, (Other way, if
CPU counts to MSI-X vector count ratio is something like X:1, where X > 1)
then 'exact' irqbalance policy OR rq_affinity = 2 won't help to avoid CPU
hard/soft lockups. There won't be any one to one mapping between
CPU to MSI-X vector instead one MSI-X interrupt (or reply descriptor queue)
is shared with group/set of CPUs and there is a possibility of having a
loop in the IO path within that CPU group and may observe lockups.
For example: Consider a system having two NUMA nodes and each node having
four logical CPUs and also consider that number of MSI-X vectors enabled on
the HBA is two, then CPUs count to MSI-X vector count ratio as 4:1.
e.g.
MSI-X vector 0 is affinity to CPU 0, CPU 1, CPU 2 & CPU 3 of NUMA node 0 and
MSI-X vector 1 is affinity to CPU 4, CPU 5, CPU 6 & CPU 7 of NUMA node 1.
numactl --hardware
available: 2 nodes (0-1)
node 0 cpus: 0 1 2 3 --> MSI-X 0
node 0 size: 65536 MB
node 0 free: 63176 MB
node 1 cpus: 4 5 6 7 --> MSI-X 1
node 1 size: 65536 MB
node 1 free: 63176 MB
Assume that user started an application which uses all the CPUs of NUMA
node 0 for issuing the IOs. Only one CPU from affinity list (it can be any
cpu since this behavior depends upon irqbalance) CPU0 will receive the
interrupts from MSI-X 0 for all the IOs. Eventually, CPU 0 IO submission
percentage will be decreasing and ISR processing percentage will be
increasing as it is more busy with processing the interrupts. Gradually IO
submission percentage on CPU 0 will be zero and it's ISR processing
percentage will be 100% as IO loop has already formed within the
NUMA node 0, i.e. CPU 1, CPU 2 & CPU 3 will be continuously busy with
submitting the heavy IOs and only CPU 0 is busy in the ISR path as it
always find the valid reply descriptor in the reply descriptor queue.
Eventually, we will observe the hard lockup here.
Chances of occurring of hard/soft lockups are directly proportional to
value of X. If value of X is high, then chances of observing CPU lockups is
high.
Solution:
Use IRQ poll interface defined in "irq_poll.c".
megaraid_sas driver will execute ISR routine in softirq context and it will
always quit the loop based on budget provided in IRQ poll interface.
Driver will switch to IRQ poll only when more than a threshold number of
reply descriptors are handled in one ISR. Currently threshold is set as
1/4th of HBA queue depth.
In these scenarios (i.e. where CPUs count to MSI-X vectors count ratio is
X:1 (where X > 1)), IRQ poll interface will avoid CPU hard lockups due to
voluntary exit from the reply queue processing based on budget.
Note - Only one MSI-X vector is busy doing processing.
Select CONFIG_IRQ_POLL from driver Kconfig for driver compilation.
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
While an online controller reset(OCR) is in progress, there is short
duration where all access to controller's PCI config space from the host
needs to be blocked. This is due to a hardware limitation of MegaRAID
controllers.
With this patch, driver will block all access to controller's config space
from userland applications by calling pci_cfg_access_lock() while OCR is in
progress and unlocking after controller comes back to ready state.
Added helper function which locks the config space before initiating OCR
and wait for controller to become READY.
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
No functional change. This patch reworks code around controller reset path
which gets rid of a couple of goto labels. This is in preparation for the
next patch which adds PCI config space access locking while controller
reset is in progress.
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
