On 23/02/2021 10:16, John Garry wrote:
On 22/02/2021 13:23, Hannes Reinecke wrote:
Hi all,
+
quite some drivers use internal commands for various purposes, most
commonly sending TMFs or querying the HBA status.
While these commands use the same submission mechanism than normal
I/O commands, they will not be counted as outstanding commands,
requiring those drivers to implement their own mechanism to figure
out outstanding commands.
The block layer already has the concept of 'reserved' tags for
precisely this purpose, namely non-I/O tags which live off a separate
tag pool. That guarantees that these commands can always be sent,
and won't be influenced by tag starvation from the I/O tag pool.
This patchset enables the use of reserved tags for the SCSI midlayer
by allocating a virtual LUN for the HBA itself which just serves
as a resource to allocate valid tags from.
This removes quite some hacks which were required for some
drivers (eg. fnic or snic), and allows the use of tagset
iterators within the drivers.
The entire patchset can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/hare/scsi-devel.git
reserved-tags.v7
Thanks for doing this, I'll have a look.
So I got this working eventually for hisi_sas - a few fixes needed:
https://github.com/hisilicon/kernel-dev/commits/private-topic-sas-5.11-resv7
I'll have a look at the core patches tomorrow. However, at this point,
how about convert just a couple of drivers (the ones which you can test)
to get it merged as a start? 31 patches is too many.
thanks,
John
