panic: sleeping in an epoch section

[Hans Petter Selasky]

On 2019-10-09 06:36, Yuri Pankov wrote:
> Tried updating from r353072 to r353334 and getting the following panic 
> reproducibly on boot (starting dhclient?):
> 
> panic: sleeping in an epoch section
> cpuid = 5
> time = 1570591558
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 
> 0xfffffe00af780140
> vpanic() at vpanic+0x19d/frame 0xfffffe00af780190
> panic() at panic+0x43/frame 0xfffffe00af7801f0
> _sleep() at _sleep+0x463/frame 0xfffffe00af780290
> pause_sbt() at pause_sbt+0x10f/frame 0xfffffe00af7802d0
> e1000_write_phy_reg_mdic() at e1000_write_phy_reg_mdic+0xee/frame 
> 0xfffffe00af780310
> e1000_enable_phy_wakeup_reg_access_bm() at 
> e1000_enable_phy_wakeup_reg_access_bm+0x2b/frame 0xfffffe00af780330
> e1000_update_mc_addr_list_pch2lan() at 
> e1000_update_mc_addr_list_pch2lan+0x3a/frame 0xfffffe00af780370
> em_if_multi_set() at em_if_multi_set+0x1d4/frame 0xfffffe00af7803c0
> iflib_if_ioctl() at iflib_if_ioctl+0x100/frame 0xfffffe00af780430
> if_addmulti() at if_addmulti+0x2af/frame 0xfffffe00af7804d0
> in_joingroup_locked() at in_joingroup_locked+0x235/frame 0xfffffe00af780570
> in_joingroup() at in_joingroup+0x5c/frame 0xfffffe00af7805d0
> in_control() at in_control+0xadf/frame 0xfffffe00af780680
> ifioctl() at ifioctl+0x40f/frame 0xfffffe00af780750
> kern_ioctl() at kern_ioctl+0x295/frame 0xfffffe00af7807b0
> sys_ioctl() at sys_ioctl+0x15d/frame 0xfffffe00af780880
> amd64_syscall() at amd64_syscall+0x2b9/frame 0xfffffe00af7809b0
> fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe00af7809b0
> --- syscall (54, FreeBSD ELF64, sys_ioctl), rip = 0x80048051a, rsp = 
> 0x7fffffffe3e8, rbp = 0x7fffffffe430 ---

The SIOCADDMULTI if_ioctl() is not allowed to sleep, because it can be 
called from the fast-path, so this is a bug in e1000 driver. Does the 
attached patch workaround the issue?

--HPS
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