qed: put cond_resched() in qed_dmae_operation_wait()

JIRA: https://issues.redhat.com/browse/RHEL-6372

commit 2efeaf1
Author: Michal Schmidt <mschmidt@redhat.com>
Date:   Mon Sep 30 22:13:07 2024 +0200

    qed: put cond_resched() in qed_dmae_operation_wait()

    It is OK to sleep in qed_dmae_operation_wait, because it is called only
    in process context, while holding p_hwfn->dmae_info.mutex from one of
    the qed_dmae_{host,grc}2{host,grc} functions.
    The udelay(DMAE_MIN_WAIT_TIME=2) in the function is too short to replace
    with usleep_range, but at least it's a suitable point for checking if we
    should give up the CPU with cond_resched().

    This lowers the latency caused by 'ethtool -d' from 10 ms to less than
    2 ms on my test system with voluntary preemption.

    Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
    Link: https://patch.msgid.link/20240930201307.330692-5-mschmidt@redhat.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>

Author: michich

drivers/net/ethernet/qlogic/qed/qed_hw.c

@@ -578,6 +578,7 @@ static int qed_dmae_operation_wait(struct qed_hwfn *p_hwfn)
 	barrier();
 	while (*p_hwfn->dmae_info.p_completion_word != DMAE_COMPLETION_VAL) {
 		udelay(DMAE_MIN_WAIT_TIME);
+		cond_resched();
 		if (++wait_cnt > wait_cnt_limit) {
 			DP_NOTICE(p_hwfn->cdev,
 				  "Timed-out waiting for operation to complete. Completion word is 0x%08x expected 0x%08x.\n",