linux-kernel - Re: [Linux-usb-users] OHCI root_port

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20071009185957.94150236A37@adsl-69-226-248-13.dsl.pltn13.pacbell.net>
Date:	Tue, 09 Oct 2007 11:59:57 -0700
From:	David Brownell <david-b@...bell.net>
To:	stern@...land.harvard.edu, greg@...ah.com
Cc:	linux-usb-users@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, davem@...emloft.net
Subject: Re: [Linux-usb-users] OHCI root_port_reset() deadly loop...

> Here is a proposed patch.  I haven't tried running it, but it compiles 
> okay.

Looks about right, too; thanks.  Minor comments:

> --- usb-2.6.orig/drivers/usb/core/hcd.h
> +++ usb-2.6/drivers/usb/core/hcd.h
> @@ -470,5 +472,9 @@ static inline void usbmon_urb_complete(s
>  		: (in_interrupt () ? "in_interrupt" : "can sleep"))
>  
>  
> -#endif /* __KERNEL__ */
> +/* Mutual exclusion for EHCI CF initialization.  This interferes with
> + * port reset on some companion controllers.
> + */
> +extern struct rw_semaphore ehci_cf_port_reset_rwsem;

You have two copies of that comment; I'd drop this one, and add a
better one around CF initialization.

What I'd have here is a comment that this symbol is exported ONLY
for use by the EHCI driver, trespassers will be violated, etc.


> --- usb-2.6.orig/drivers/usb/host/ehci-hcd.c
> +++ usb-2.6/drivers/usb/host/ehci-hcd.c
> @@ -646,9 +646,11 @@ static int ehci_run (struct usb_hcd *hcd
>  	 * involved with the root hub.  (Except where one is integrated,
>  	 * and there's no companion controller unless maybe for USB OTG.)
>  	 */
> +	down_write(&ehci_cf_port_reset_rwsem);
>  	hcd->state = HC_STATE_RUNNING;
>  	ehci_writel(ehci, FLAG_CF, &ehci->regs->configured_flag);
>  	ehci_readl(ehci, &ehci->regs->command);	/* unblock posted writes */
> +	up_write(&ehci_cf_port_reset_rwsem);

That deserves a comment about how CF and companion port resets
don't mix well.

... assuming this does check out as the problem, which I expect
it will.

- Dave

>  
>  	temp = HC_VERSION(ehci_readl(ehci, &ehci->caps->hc_capbase));
>  	ehci_info (ehci,
>
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/