System crashes due to race condition in `bfa` driver while trying to update `dev_loss_tmo` value .

Issue

• System crashes due to race condition in bfa driver while trying to update dev_loss_tmo value . dev_loss_tmo value is being set through udev rules.

Process stack which was trying to update the dev_loss_tmo through udev rules for the newly added remote port

crash> bt
PID: 11825  TASK: ffff9a8df784b180  CPU: 27  COMMAND: "systemd-udevd"
 #0 [ffff9a824a433a48] machine_kexec at ffffffffb30662c4
 #1 [ffff9a824a433aa8] __crash_kexec at ffffffffb3122532
 #2 [ffff9a824a433b78] crash_kexec at ffffffffb3122620
 #3 [ffff9a824a433b90] oops_end at ffffffffb378d798
 #4 [ffff9a824a433bb8] no_context at ffffffffb3075d14
 #5 [ffff9a824a433c08] __bad_area_nosemaphore at ffffffffb3075fe2
 #6 [ffff9a824a433c58] bad_area at ffffffffb377ca71
 #7 [ffff9a824a433c80] __do_page_fault at ffffffffb37908b7
 #8 [ffff9a824a433cf0] do_page_fault at ffffffffb3790975
 #9 [ffff9a824a433d20] page_fault at ffffffffb378c778
    [exception RIP: bfad_im_set_rport_loss_tmo+25]
    RIP: ffffffffc041dde9  RSP: ffff9a824a433dd0  RFLAGS: 00010217
    RAX: 0000000000000000  RBX: ffff9a9e3da88800  RCX: 0000000000000000
    RDX: ffff9a7ebb8bb000  RSI: 000000007fffffff  RDI: ffff9a9e3da88800
    RBP: ffff9a824a433de0   R8: 000000007fffffff   R9: 000000000000000a
    R10: 000000000000000a  R11: f000000000000000  R12: 000000007fffffff
    R13: 000000007fffffff  R14: ffff9a63e5767900  R15: ffff9a824a433ee8
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
#10 [ffff9a824a433de8] fc_rport_set_dev_loss_tmo at ffffffffc01c4c5e [scsi_transport_fc]
#11 [ffff9a824a433e10] store_fc_rport_dev_loss_tmo at ffffffffc01c4cee [scsi_transport_fc]
#12 [ffff9a824a433e40] dev_attr_store at ffffffffb34b58ab
#13 [ffff9a824a433e50] sysfs_kf_write at ffffffffb32db522
#14 [ffff9a824a433e60] kernfs_fop_write at ffffffffb32dab0b
#15 [ffff9a824a433e98] vfs_write at ffffffffb324e080
#16 [ffff9a824a433ed8] sys_write at ffffffffb324ee5f
#17 [ffff9a824a433f20] symev_write at ffffffffc077a4e6 [symev_rh_ES_7_3_10_0_862_9_1_el7_x86_64]
#18 [ffff9a824a433f50] system_call_fastpath at ffffffffb3795f92
    RIP: 00007ffff6c3ca90  RSP: 00007fffffff91e0  RFLAGS: 00010246
    RAX: 0000000000000001  RBX: 000000000000000a  RCX: 0000000000000000
    RDX: 000000000000000a  RSI: 00007ffff7ff5000  RDI: 0000000000000008
    RBP: 00007ffff7ff5000   R8: 0000555555815d40   R9: 00007ffff7fe88c0
    R10: 0000000000000022  R11: 0000000000000246  R12: 0000555555815c60
    R13: 000000000000000a  R14: 00005555558086c0  R15: 0000555555595b84