From: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
Felipe Balbi <balbi@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Dmitry Bogdanov <d.bogdanov@yadro.com>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"target-devel@vger.kernel.org" <target-devel@vger.kernel.org>
Subject: Re: [PATCH v2 11/25] usb: gadget: f_tcm: Execute command on write completion
Date: Mon, 29 Aug 2022 21:47:41 +0000 [thread overview]
Message-ID: <20220829214738.g4sazbxapgmlyksa@synopsys.com> (raw)
In-Reply-To: <Yw0YP1qUYAw6inMJ@linutronix.de>
On Mon, Aug 29, 2022, Sebastian Andrzej Siewior wrote:
> On 2022-08-26 18:37:36 [+0000], Thinh Nguyen wrote:
> > On Fri, Aug 26, 2022, Sebastian Andrzej Siewior wrote:
> > > On 2022-07-18 18:27:12 [-0700], Thinh Nguyen wrote:
> > > > index 6fea80afe2d7..ec83f2f9a858 100644
> > > > --- a/drivers/usb/gadget/function/f_tcm.c
> > > > +++ b/drivers/usb/gadget/function/f_tcm.c
> > > > @@ -955,7 +949,7 @@ static void usbg_data_write_cmpl(struct usb_ep *ep, struct usb_request *req)
> > > > se_cmd->data_length);
> > > > }
> > > >
> > > > - complete(&cmd->write_complete);
> > > > + target_execute_cmd(se_cmd);
> > >
> > > usbg_data_write_cmpl() is invoked from interrupt service routing which
> > > may run with disabled interrupts. From looking at target_execute_cmd():
> >
> > It will always be called with interrupts disabled as documented in
> > usb_request API.
> >
> > > | void target_execute_cmd(struct se_cmd *cmd)
> > > | {
> > > …
> > > | spin_lock_irq(&cmd->t_state_lock);
> > > …
> > > | spin_unlock_irq(&cmd->t_state_lock);
> > > …
> > > | }
> > >
> > > which means interrupts will remain open after leaving
> > > target_execute_cmd(). Now, why didn't the WARN_ONCE() in
> > > __handle_irq_event_percpu() trigger? Am I missing something?
> > >
> > > > return;
> > >
> >
> > Since target_execute_cmd() is called in usbg_data_write_cmpl(),
> > interrupts are still disabled.
>
> but you do realize that target_execute_cmd() will leave with enabled
> interrupts and this is not desired? I _think_ this was the reason why I
> ended up with the wait+complete construct instead of invoking this
> function directly.
> An _irqsave() in target_execute_cmd() would probably be all you need
> here.
>
Ok. Maybe we should make a change in the target_execute_cmd() then. It
seems unreasonable to force the caller to workaround this such as the
wait+complete construct you did (and I don't recall we have changes in
place to know/guarantee that interrupts are enabled before executing
target_execute_cmd() previously either).
For the dwc3, we masked the interrupt at this point, so interrupt won't
be asserted here.
Thanks,
Thinh
next prev parent reply other threads:[~2022-08-29 21:48 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-19 1:26 [PATCH v2 00/25] usb: gadget: f_tcm: Enhance UASP driver Thinh Nguyen
2022-07-19 1:26 ` [PATCH v2 01/25] target: Add overlapped response to tmrsp_table Thinh Nguyen
2022-07-19 1:26 ` [PATCH v2 02/25] target: Add common TMR enum Thinh Nguyen
2022-07-19 1:26 ` [PATCH v2 03/25] usb: gadget: f_tcm: Increase stream count Thinh Nguyen
2022-07-19 9:02 ` Sergei Shtylyov
2022-07-19 1:26 ` [PATCH v2 04/25] usb: gadget: f_tcm: Increase bMaxBurst Thinh Nguyen
2022-07-19 1:26 ` [PATCH v2 05/25] usb: gadget: f_tcm: Don't set static stream_id Thinh Nguyen
2022-07-19 1:26 ` [PATCH v2 06/25] usb: gadget: f_tcm: Allocate matching number of commands to streams Thinh Nguyen
2022-07-19 1:26 ` [PATCH v2 07/25] usb: gadget: f_tcm: Limit number of sessions Thinh Nguyen
2022-07-19 1:26 ` [PATCH v2 08/25] usb: gadget: f_tcm: Handle multiple commands in parallel Thinh Nguyen
2022-07-19 1:27 ` [PATCH v2 09/25] usb: gadget: f_tcm: Use extra number of commands Thinh Nguyen
2022-07-19 1:27 ` [PATCH v2 10/25] usb: gadget: f_tcm: Return ATA cmd direction Thinh Nguyen
2022-07-19 1:27 ` [PATCH v2 11/25] usb: gadget: f_tcm: Execute command on write completion Thinh Nguyen
2022-08-26 7:00 ` Sebastian Andrzej Siewior
2022-08-26 18:37 ` Thinh Nguyen
2022-08-29 19:49 ` Sebastian Andrzej Siewior
2022-08-29 21:47 ` Thinh Nguyen [this message]
2022-08-30 10:03 ` Sebastian Andrzej Siewior
2022-07-19 1:27 ` [PATCH v2 12/25] usb: gadget: f_tcm: Minor cleanup redundant code Thinh Nguyen
2022-07-19 1:27 ` [PATCH v2 13/25] usb: gadget: f_tcm: Don't free command immediately Thinh Nguyen
2022-07-19 1:27 ` [PATCH v2 14/25] usb: gadget: f_tcm: Translate error to sense Thinh Nguyen
2022-07-19 1:27 ` [PATCH v2 15/25] usb: gadget: f_tcm: Cleanup unused variable Thinh Nguyen
2022-08-26 7:17 ` Sebastian Andrzej Siewior
2022-08-26 18:41 ` Thinh Nguyen
2022-07-19 1:27 ` [PATCH v2 16/25] usb: gadget: f_tcm: Update state on data write Thinh Nguyen
2022-08-26 7:22 ` Sebastian Andrzej Siewior
2022-08-26 19:01 ` Thinh Nguyen
2022-07-19 1:27 ` [PATCH v2 17/25] usb: gadget: f_tcm: Handle abort command Thinh Nguyen
2022-08-26 7:48 ` Sebastian Andrzej Siewior
2022-08-26 19:04 ` Thinh Nguyen
2022-07-19 1:27 ` [PATCH v2 18/25] usb: gadget: f_tcm: Cleanup requests on ep disable Thinh Nguyen
2022-07-19 1:28 ` [PATCH v2 19/25] usb: gadget: f_tcm: Decrement command ref count on cleanup Thinh Nguyen
2022-07-19 1:28 ` [PATCH v2 20/25] usb: gadget: f_tcm: Save CPU ID per command Thinh Nguyen
2022-07-19 1:28 ` [PATCH v2 21/25] usb: gadget: f_tcm: Get stream by tag Thinh Nguyen
2022-08-26 9:06 ` Sebastian Andrzej Siewior
2022-08-26 19:05 ` Thinh Nguyen
2022-07-19 1:28 ` [PATCH v2 22/25] usb: gadget: f_tcm: Send sense on cancelled transfer Thinh Nguyen
2022-07-19 1:28 ` [PATCH v2 23/25] usb: gadget: f_tcm: Handle TASK_MANAGEMENT commands Thinh Nguyen
2022-07-19 1:28 ` [PATCH v2 24/25] usb: gadget: f_tcm: Check overlapped command Thinh Nguyen
2022-08-26 10:46 ` Sebastian Andrzej Siewior
2022-08-26 19:27 ` Thinh Nguyen
2022-07-19 1:28 ` [PATCH v2 25/25] usb: gadget: f_tcm: Comply with UAS Task Management requirement Thinh Nguyen
2022-08-19 8:31 ` [PATCH v2 00/25] usb: gadget: f_tcm: Enhance UASP driver Greg Kroah-Hartman
2022-08-19 17:18 ` Thinh Nguyen
2022-08-26 2:34 ` Thinh Nguyen
2022-08-26 10:52 ` Sebastian Andrzej Siewior
2022-08-26 19:36 ` Thinh Nguyen
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