From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from netrider.rowland.org (netrider.rowland.org [192.131.102.5]) by mx.groups.io with SMTP id smtpd.web11.29852.1602462431058180474 for ; Sun, 11 Oct 2020 17:27:11 -0700 Authentication-Results: mx.groups.io; dkim=missing; spf=pass (domain: netrider.rowland.org, ip: 192.131.102.5, mailfrom: stern+5f965aec@netrider.rowland.org) Received: (qmail 615163 invoked by uid 1000); 11 Oct 2020 20:27:09 -0400 Date: Sun, 11 Oct 2020 20:27:09 -0400 From: Alan Stern To: Sudip Mukherjee Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-safety@lists.elisa.tech, linux-usb@vger.kernel.org Subject: Re: [PATCH] usb: host: ehci-sched: add comment about find_tt() not returning error Message-ID: <20201012002709.GA614913@rowland.harvard.edu> References: <20201011205008.24369-1-sudipm.mukherjee@gmail.com> MIME-Version: 1.0 In-Reply-To: <20201011205008.24369-1-sudipm.mukherjee@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Sun, Oct 11, 2020 at 09:50:08PM +0100, Sudip Mukherjee wrote: > Add a comment explaining why find_tt() will not return error even though > find_tt() is checking for NULL and other errors. > > Signed-off-by: Sudip Mukherjee > --- > drivers/usb/host/ehci-sched.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c > index 6dfb242f9a4b..0f85aa9b2fb1 100644 > --- a/drivers/usb/host/ehci-sched.c > +++ b/drivers/usb/host/ehci-sched.c > @@ -244,6 +244,12 @@ static void reserve_release_intr_bandwidth(struct ehci_hcd *ehci, > > /* FS/LS bus bandwidth */ > if (tt_usecs) { > + /* > + * find_tt() will not return any error here as we have > + * already called find_tt() before calling this function > + * and checked for any error return. The previous call > + * would have created the data structure. > + */ > tt = find_tt(qh->ps.udev); > if (sign > 0) > list_add_tail(&qh->ps.ps_list, &tt->ps_list); > @@ -1337,6 +1343,12 @@ static void reserve_release_iso_bandwidth(struct ehci_hcd *ehci, > } > } > > + /* > + * find_tt() will not return any error here as we have > + * already called find_tt() before calling this function > + * and checked for any error return. The previous call > + * would have created the data structure. > + */ > tt = find_tt(stream->ps.udev); > if (sign > 0) > list_add_tail(&stream->ps.ps_list, &tt->ps_list); Acked-by: Alan Stern