scsi: qedf: Add check to synchronize abort and flush

A race condition was observed between qedf_cleanup_fcport() and
qedf_process_error_detect()->qedf_initiate_abts():

 [2069091.203145] BUG: unable to handle kernel NULL pointer dereference at 0000000000000030
 [2069091.213100] IP: [<ffffffffc0666cc6>] qedf_process_error_detect+0x96/0x130 [qedf]
 [2069091.223391] PGD 1943049067 PUD 194304e067 PMD 0
 [2069091.233420] Oops: 0000 [xen-troops#1] SMP
 [2069091.361820] CPU: 1 PID: 14751 Comm: kworker/1:46 Kdump: loaded Tainted: P           OE  ------------   3.10.0-1160.25.1.el7.x86_64 xen-troops#1
 [2069091.388474] Hardware name: HPE Synergy 480 Gen10/Synergy 480 Gen10 Compute Module, BIOS I42 04/08/2020
 [2069091.402148] Workqueue: qedf_io_wq qedf_fp_io_handler [qedf]
 [2069091.415780] task: ffff9bb9f5190000 ti: ffff9bacaef9c000 task.ti: ffff9bacaef9c000
 [2069091.429590] RIP: 0010:[<ffffffffc0666cc6>]  [<ffffffffc0666cc6>] qedf_process_error_detect+0x96/0x130 [qedf]
 [2069091.443666] RSP: 0018:ffff9bacaef9fdb8  EFLAGS: 00010246
 [2069091.457692] RAX: 0000000000000000 RBX: ffff9bbbbbfb18a0 RCX: ffffffffc0672310
 [2069091.471997] RDX: 00000000000005de RSI: ffffffffc066e7f0 RDI: ffff9beb3f4538d8
 [2069091.486130] RBP: ffff9bacaef9fdd8 R08: 0000000000006000 R09: 0000000000006000
 [2069091.500321] R10: 0000000000001551 R11: ffffb582996ffff8 R12: ffffb5829b39cc18
 [2069091.514779] R13: ffff9badab380c28 R14: ffffd5827f643900 R15: 0000000000000040
 [2069091.529472] FS:  0000000000000000(0000) GS:ffff9beb3f440000(0000) knlGS:0000000000000000
 [2069091.543926] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 [2069091.558942] CR2: 0000000000000030 CR3: 000000193b9a2000 CR4: 00000000007607e0
 [2069091.573424] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 [2069091.587876] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 [2069091.602007] PKRU: 00000000
 [2069091.616010] Call Trace:
 [2069091.629902]  [<ffffffffc0663969>] qedf_process_cqe+0x109/0x2e0 [qedf]
 [2069091.643941]  [<ffffffffc0663b66>] qedf_fp_io_handler+0x26/0x60 [qedf]
 [2069091.657948]  [<ffffffff85ebddcf>] process_one_work+0x17f/0x440
 [2069091.672111]  [<ffffffff85ebeee6>] worker_thread+0x126/0x3c0
 [2069091.686057]  [<ffffffff85ebedc0>] ? manage_workers.isra.26+0x2a0/0x2a0
 [2069091.700033]  [<ffffffff85ec5da1>] kthread+0xd1/0xe0
 [2069091.713891]  [<ffffffff85ec5cd0>] ? insert_kthread_work+0x40/0x40

Add check in qedf_process_error_detect(). When flush is active, let the
cmds be completed from the cleanup contex.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Javed Hasan <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

Author: javed-h

drivers/scsi/qedf/qedf_io.c

@@ -1515,9 +1515,19 @@ void qedf_process_error_detect(struct qedf_ctx *qedf, struct fcoe_cqe *cqe,
 {
 	int rval;
 
+	if (io_req == NULL) {
+		QEDF_INFO(NULL, QEDF_LOG_IO, "io_req is NULL.\n");
+		return;
+	}
+
+	if (io_req->fcport == NULL) {
+		QEDF_INFO(NULL, QEDF_LOG_IO, "fcport is NULL.\n");
+		return;
+	}
+
 	if (!cqe) {
 		QEDF_INFO(&qedf->dbg_ctx, QEDF_LOG_IO,
-			  "cqe is NULL for io_req %p\n", io_req);
+			"cqe is NULL for io_req %p\n", io_req);
 		return;
 	}
 
@@ -1533,6 +1543,16 @@ void qedf_process_error_detect(struct qedf_ctx *qedf, struct fcoe_cqe *cqe,
 		  le32_to_cpu(cqe->cqe_info.err_info.rx_buf_off),
 		  le32_to_cpu(cqe->cqe_info.err_info.rx_id));
 
+	/* When flush is active, let the cmds be flushed out from the cleanup context */
+	if (test_bit(QEDF_RPORT_IN_TARGET_RESET, &io_req->fcport->flags) ||
+		(test_bit(QEDF_RPORT_IN_LUN_RESET, &io_req->fcport->flags) &&
+		 io_req->sc_cmd->device->lun == (u64)io_req->fcport->lun_reset_lun)) {
+		QEDF_ERR(&qedf->dbg_ctx,
+			"Dropping EQE for xid=0x%x as fcport is flushing",
+			io_req->xid);
+		return;
+	}
+
 	if (qedf->stop_io_on_error) {
 		qedf_stop_all_io(qedf);
 		return;