commit 4f7f5551a7 upstream.
System may crash after unloading ipmi_si.ko module
because a timer may remain and fire after the module cleaned up resources.
cleanup_one_si() contains the following processing.
/*
* Make sure that interrupts, the timer and the thread are
* stopped and will not run again.
*/
if (to_clean->irq_cleanup)
to_clean->irq_cleanup(to_clean);
wait_for_timer_and_thread(to_clean);
/*
* Timeouts are stopped, now make sure the interrupts are off
* in the BMC. Note that timers and CPU interrupts are off,
* so no need for locks.
*/
while (to_clean->curr_msg || (to_clean->si_state != SI_NORMAL)) {
poll(to_clean);
schedule_timeout_uninterruptible(1);
}
si_state changes as following in the while loop calling poll(to_clean).
SI_GETTING_MESSAGES
=> SI_CHECKING_ENABLES
=> SI_SETTING_ENABLES
=> SI_GETTING_EVENTS
=> SI_NORMAL
As written in the code comments above,
timers are expected to stop before the polling loop and not to run again.
But the timer is set again in the following process
when si_state becomes SI_SETTING_ENABLES.
=> poll
=> smi_event_handler
=> handle_transaction_done
// smi_info->si_state == SI_SETTING_ENABLES
=> start_getting_events
=> start_new_msg
=> smi_mod_timer
=> mod_timer
As a result, before the timer set in start_new_msg() expires,
the polling loop may see si_state becoming SI_NORMAL
and the module clean-up finishes.
For example, hard LOCKUP and panic occurred as following.
smi_timeout was called after smi_event_handler,
kcs_event and hangs at port_inb()
trying to access I/O port after release.
[exception RIP: port_inb+19]
RIP: ffffffffc0473053 RSP: ffff88069fdc3d80 RFLAGS: 00000006
RAX: ffff8806800f8e00 RBX: ffff880682bd9400 RCX: 0000000000000000
RDX: 0000000000000ca3 RSI: 0000000000000ca3 RDI: ffff8806800f8e40
RBP: ffff88069fdc3d80 R8: ffffffff81d86dfc R9: ffffffff81e36426
R10: 00000000000509f0 R11: 0000000000100000 R12: 0000000000]:000000
R13: 0000000000000000 R14: 0000000000000246 R15: ffff8806800f8e00
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0000
--- <NMI exception stack> ---
To fix the problem I defined a flag, timer_can_start,
as member of struct smi_info.
The flag is enabled immediately after initializing the timer
and disabled immediately before waiting for timer deletion.
Fixes: 0cfec916e8 ("ipmi: Start the timer and thread on internal msgs")
Signed-off-by: Yamazaki Masamitsu <m-yamazaki@ah.jp.nec.com>
[Adjusted for recent changes in the driver.]
[Some fairly major changes went into the IPMI driver in 4.15, so this
required a backport as the code had changed and moved to a different
file. The 4.14 version of this patch moved some code under an
if statement and there was an API change causing it to not apply to
4.4-4.6.]
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
99962affcb