scsi: target: core: Replace in_interrupt() usage in target_submit_cmd_map_sgls()

target_submit_cmd_map_sgls() uses in_interrupt() to crash if it returns
true.

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

The usage of in_interrupt() is clearly for debugging. might_sleep() is
better at this because it also detects other contexts in which it is not
allowed to sleep, like preempt-disabled section.

Replace BUG_ON(in_interrupt) with might_sleep().

Link: https://lore.kernel.org/r/20201220203638.43615-6-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/target/target_core_transport.c

@@ -1613,10 +1613,11 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess
 	sense_reason_t rc;
 	int ret;
 
+	might_sleep();
+
 	se_tpg = se_sess->se_tpg;
 	BUG_ON(!se_tpg);
 	BUG_ON(se_cmd->se_tfo || se_cmd->se_sess);
-	BUG_ON(in_interrupt());
 
 	if (flags & TARGET_SCF_USE_CPUID)
 		se_cmd->se_cmd_flags |= SCF_USE_CPUID;