Commit 3052809a authored by Jim Harris's avatar Jim Harris Committed by Tomasz Zawadzki
Browse files

ublk: add comment clarifying use of SQPOLL for ctrl ring 



We need to use SQPOLL on the ctrl ring for now, due to
a bug in kernels <= 6.1.  This ring is used very
infrequently, so the workaround has no real effect
on performance.

Signed-off-by: default avatarJim Harris <james.r.harris@intel.com>
Change-Id: Ia5e65a6edb7b1b6c4c945ebda8941f98c2bcdb07
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16620


Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: default avatarKonrad Sztyber <konrad.sztyber@intel.com>
Reviewed-by: default avatarChangpeng Liu <changpeng.liu@intel.com>
parent addc5457

lib/ublk/ublk.c

+3 −0
Original line number Diff line number Diff line
@@ -344,6 +344,9 @@ ublk_open(void) 
		return -rc;

	}



	/* We need to set SQPOLL for kernels 6.1 and earlier, since they would not defer ublk ctrl

	 * ring processing to a workqueue.  Ctrl ring processing is minimal, so SQPOLL is fine.

	 */

	rc = ublk_setup_ring(UBLK_CTRL_RING_DEPTH, &g_ublk_tgt.ctrl_ring,

			     IORING_SETUP_SQE128 | IORING_SETUP_SQPOLL);

	if (rc < 0) {