[PATCH 2/3] lpfc: Fix a kernel warning triggered by lpfc_sli4_enable_intr()

From: Bart Van Assche <bvanassche@acm.org>
To: "Martin K . Petersen" <martin.petersen@oracle.com>,
	"James E . J . Bottomley" <jejb@linux.vnet.ibm.com>
Cc: James Smart <jsmart2021@gmail.com>,
	linux-scsi@vger.kernel.org, Bart Van Assche <bvanassche@acm.org>
Subject: [PATCH 2/3] lpfc: Fix a kernel warning triggered by lpfc_sli4_enable_intr()
Date: Wed,  6 Nov 2019 21:21:56 -0800	[thread overview]
Message-ID: <20191107052158.25788-4-bvanassche@acm.org> (raw)
In-Reply-To: <20191107052158.25788-1-bvanassche@acm.org>

Fix the following lockdep warning:

============================================
WARNING: possible recursive locking detected
5.4.0-rc6-dbg+ #2 Not tainted
--------------------------------------------
systemd-udevd/130 is trying to acquire lock:
ffffffff826b05d0 (cpu_hotplug_lock.rw_sem){++++}, at: irq_calc_affinity_vectors+0x63/0x90

but task is already holding lock:

ffffffff826b05d0 (cpu_hotplug_lock.rw_sem){++++}, at: lpfc_sli4_enable_intr+0x422/0xd50 [lpfc]

other info that might help us debug this:

 Possible unsafe locking scenario:
       CPU0
       ----
  lock(cpu_hotplug_lock.rw_sem);
  lock(cpu_hotplug_lock.rw_sem);

*** DEADLOCK ***
 May be due to missing lock nesting notation
2 locks held by systemd-udevd/130:
 #0: ffff8880d53fe210 (&dev->mutex){....}, at: __device_driver_lock+0x4a/0x70
 #1: ffffffff826b05d0 (cpu_hotplug_lock.rw_sem){++++}, at: lpfc_sli4_enable_intr+0x422/0xd50 [lpfc]

stack backtrace:
CPU: 1 PID: 130 Comm: systemd-udevd Not tainted 5.4.0-rc6-dbg+ #2
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
Call Trace:
 dump_stack+0xa5/0xe6
 __lock_acquire.cold+0xf7/0x23a
 lock_acquire+0x106/0x240
 cpus_read_lock+0x41/0xe0
 irq_calc_affinity_vectors+0x63/0x90
 __pci_enable_msix_range+0x10a/0x950
 pci_alloc_irq_vectors_affinity+0x144/0x210
 lpfc_sli4_enable_intr+0x4b2/0xd50 [lpfc]
 lpfc_pci_probe_one+0x1411/0x22b0 [lpfc]
 local_pci_probe+0x7c/0xc0
 pci_device_probe+0x25d/0x390
 really_probe+0x170/0x510
 driver_probe_device+0x127/0x190
 device_driver_attach+0x98/0xa0
 __driver_attach+0xb6/0x1a0
 bus_for_each_dev+0x100/0x150
 driver_attach+0x31/0x40
 bus_add_driver+0x246/0x300
 driver_register+0xe0/0x170
 __pci_register_driver+0xde/0xf0
 lpfc_init+0x134/0x1000 [lpfc]
 do_one_initcall+0xda/0x47e
 do_init_module+0x10a/0x3b0
 load_module+0x4318/0x47c0
 __do_sys_finit_module+0x134/0x1d0
 __x64_sys_finit_module+0x47/0x50
 do_syscall_64+0x6f/0x2e0
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fixes: dcaa21367938 ("scsi: lpfc: Change default IRQ model on AMD architectures")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/lpfc/lpfc_init.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c
index 28e6a763f106..37e57fd9ba5d 100644
--- a/drivers/scsi/lpfc/lpfc_init.c
+++ b/drivers/scsi/lpfc/lpfc_init.c
@@ -11580,9 +11580,7 @@ lpfc_sli4_enable_intr(struct lpfc_hba *phba, uint32_t cfg_mode)
 		retval = 0;
 		if (!retval) {
 			/* Now, try to enable MSI-X interrupt mode */
-			get_online_cpus();
 			retval = lpfc_sli4_enable_msix(phba);
-			put_online_cpus();
 			if (!retval) {
 				/* Indicate initialization to MSI-X mode */
 				phba->intr_type = MSIX;
-- 
2.23.0

