On Tue, Aug 20, 2019 at 02:55:29PM -0400, Tony Camuso wrote:
> I think this fixes the deadlock without messing up the message
> sequencing.
Looks good to me. Queued for next release with a backport to 5.1
Thanks,
-corey
>
> From 144aa8c3020c72a68a57f5d1496ed9a83d013087 Mon Sep 17 00:00:00 2001
> From: Tony Camuso <tcam...@redhat.com>
> Date: Tue, 20 Aug 2019 14:51:26 -0400
> Subject: [PATCH] ipmi: move message error checking to avoid deadlock
>
> In the source stack trace below, function set_need_watch tries to
> take out the same si_lock that was taken earlier by ipmi_thread.
>
> ipmi_thread() [drivers/char/ipmi/ipmi_si_intf.c:995]
> smi_event_handler() [drivers/char/ipmi/ipmi_si_intf.c:765]
> handle_transaction_done() [drivers/char/ipmi/ipmi_si_intf.c:555]
> deliver_recv_msg() [drivers/char/ipmi/ipmi_si_intf.c:283]
> ipmi_smi_msg_received() [drivers/char/ipmi/ipmi_msghandler.c:4503]
> intf_err_seq() [drivers/char/ipmi/ipmi_msghandler.c:1149]
> smi_remove_watch() [drivers/char/ipmi/ipmi_msghandler.c:999]
> set_need_watch() [drivers/char/ipmi/ipmi_si_intf.c:1066]
>
> Upstream commit e1891cffd4c4896a899337a243273f0e23c028df adds code to
> ipmi_smi_msg_received() to call smi_remove_watch() via intf_err_seq()
> and this seems to be causing the deadlock.
>
> commit e1891cffd4c4896a899337a243273f0e23c028df
> Author: Corey Minyard <cminy...@mvista.com>
> Date: Wed Oct 24 15:17:04 2018 -0500
> ipmi: Make the smi watcher be disabled immediately when not needed
>
> The fix is to put all messages in the queue and move the message
> checking code out of ipmi_smi_msg_received and into handle_one_recv_msg,
> which processes the message checking after ipmi_thread releases its
> locks.
>
> Reported by: Osamu Samukawa <osa-samuk...@tg.jp.nec.com>
> Characterized by: Kosuke Tatsukawa <ta...@ab.jp.nec.com>
> Signed-off-by: Tony Camuso <tcam...@redhat.com>
> ---
> drivers/char/ipmi/ipmi_msghandler.c | 113
> ++++++++++++++++++------------------
> 1 file changed, 56 insertions(+), 57 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_msghandler.c
> b/drivers/char/ipmi/ipmi_msghandler.c
> index 6707659cffd6..0a907cd62dc6 100644
> --- a/drivers/char/ipmi/ipmi_msghandler.c
> +++ b/drivers/char/ipmi/ipmi_msghandler.c
> @@ -4215,7 +4215,52 @@ static int handle_one_recv_msg(struct ipmi_smi *intf,
> int chan;
>
> ipmi_debug_msg("Recv:", msg->rsp, msg->rsp_size);
> - if (msg->rsp_size < 2) {
> +
> + if ((msg->data_size >= 2)
> + && (msg->data[0] == (IPMI_NETFN_APP_REQUEST << 2))
> + && (msg->data[1] == IPMI_SEND_MSG_CMD)
> + && (msg->user_data == NULL)) {
> +
> + if (intf->in_shutdown)
> + goto free_msg;
> +
> + /*
> + * This is the local response to a command send, start
> + * the timer for these. The user_data will not be
> + * NULL if this is a response send, and we will let
> + * response sends just go through.
> + */
> +
> + /*
> + * Check for errors, if we get certain errors (ones
> + * that mean basically we can try again later), we
> + * ignore them and start the timer. Otherwise we
> + * report the error immediately.
> + */
> + if ((msg->rsp_size >= 3) && (msg->rsp[2] != 0)
> + && (msg->rsp[2] != IPMI_NODE_BUSY_ERR)
> + && (msg->rsp[2] != IPMI_LOST_ARBITRATION_ERR)
> + && (msg->rsp[2] != IPMI_BUS_ERR)
> + && (msg->rsp[2] != IPMI_NAK_ON_WRITE_ERR)) {
> + int ch = msg->rsp[3] & 0xf;
> + struct ipmi_channel *chans;
> +
> + /* Got an error sending the message, handle it. */
> +
> + chans = READ_ONCE(intf->channel_list)->c;
> + if ((chans[ch].medium == IPMI_CHANNEL_MEDIUM_8023LAN)
> + || (chans[ch].medium == IPMI_CHANNEL_MEDIUM_ASYNC))
> + ipmi_inc_stat(intf, sent_lan_command_errs);
> + else
> + ipmi_inc_stat(intf, sent_ipmb_command_errs);
> + intf_err_seq(intf, msg->msgid, msg->rsp[2]);
> + } else
> + /* The message was sent, start the timer. */
> + intf_start_seq_timer(intf, msg->msgid);
> +free_msg:
> + ipmi_free_smi_msg(msg);
> +
> + } else if (msg->rsp_size < 2) {
> /* Message is too small to be correct. */
> dev_warn(intf->si_dev,
> "BMC returned too small a message for netfn %x cmd %x,
> got %d bytes\n",
> @@ -4472,62 +4517,16 @@ void ipmi_smi_msg_received(struct ipmi_smi *intf,
> unsigned long flags = 0; /* keep us warning-free. */
> int run_to_completion = intf->run_to_completion;
>
> - if ((msg->data_size >= 2)
> - && (msg->data[0] == (IPMI_NETFN_APP_REQUEST << 2))
> - && (msg->data[1] == IPMI_SEND_MSG_CMD)
> - && (msg->user_data == NULL)) {
> -
> - if (intf->in_shutdown)
> - goto free_msg;
> -
> - /*
> - * This is the local response to a command send, start
> - * the timer for these. The user_data will not be
> - * NULL if this is a response send, and we will let
> - * response sends just go through.
> - */
> -
> - /*
> - * Check for errors, if we get certain errors (ones
> - * that mean basically we can try again later), we
> - * ignore them and start the timer. Otherwise we
> - * report the error immediately.
> - */
> - if ((msg->rsp_size >= 3) && (msg->rsp[2] != 0)
> - && (msg->rsp[2] != IPMI_NODE_BUSY_ERR)
> - && (msg->rsp[2] != IPMI_LOST_ARBITRATION_ERR)
> - && (msg->rsp[2] != IPMI_BUS_ERR)
> - && (msg->rsp[2] != IPMI_NAK_ON_WRITE_ERR)) {
> - int ch = msg->rsp[3] & 0xf;
> - struct ipmi_channel *chans;
> -
> - /* Got an error sending the message, handle it. */
> -
> - chans = READ_ONCE(intf->channel_list)->c;
> - if ((chans[ch].medium == IPMI_CHANNEL_MEDIUM_8023LAN)
> - || (chans[ch].medium == IPMI_CHANNEL_MEDIUM_ASYNC))
> - ipmi_inc_stat(intf, sent_lan_command_errs);
> - else
> - ipmi_inc_stat(intf, sent_ipmb_command_errs);
> - intf_err_seq(intf, msg->msgid, msg->rsp[2]);
> - } else
> - /* The message was sent, start the timer. */
> - intf_start_seq_timer(intf, msg->msgid);
> -
> -free_msg:
> - ipmi_free_smi_msg(msg);
> - } else {
> - /*
> - * To preserve message order, we keep a queue and deliver from
> - * a tasklet.
> - */
> - if (!run_to_completion)
> - spin_lock_irqsave(&intf->waiting_rcv_msgs_lock, flags);
> - list_add_tail(&msg->link, &intf->waiting_rcv_msgs);
> - if (!run_to_completion)
> - spin_unlock_irqrestore(&intf->waiting_rcv_msgs_lock,
> - flags);
> - }
> + /*
> + * To preserve message order, we keep a queue and deliver from
> + * a tasklet.
> + */
> + if (!run_to_completion)
> + spin_lock_irqsave(&intf->waiting_rcv_msgs_lock, flags);
> + list_add_tail(&msg->link, &intf->waiting_rcv_msgs);
> + if (!run_to_completion)
> + spin_unlock_irqrestore(&intf->waiting_rcv_msgs_lock,
> + flags);
>
> if (!run_to_completion)
> spin_lock_irqsave(&intf->xmit_msgs_lock, flags);
> --
> 2.18.1
>
>
>
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