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From: Peter Chen <peter.chen@nxp.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Felipe Balbi <balbi@kernel.org>,
	"pawell@cadence.com" <pawell@cadence.com>,
	"rogerq@ti.com" <rogerq@ti.com>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	dl-linux-imx <linux-imx@nxp.com>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	Jun Li <jun.li@nxp.com>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: RE: [PATCH 1/3] usb: cdns3: gadget: suspicious implicit sign extension
Date: Wed, 28 Oct 2020 06:41:29 +0000
Message-ID: <AM8PR04MB730012810E26CEE055A4E99C8B170@AM8PR04MB7300.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20201027142123.GA1233346@rowland.harvard.edu>

 
> That's a separate issue.  I believe (but haven't checked) that the << operator
> has lower precedence than +, so the compiler interprets the expression as:
> 
> unsigned int k = 0x80 << (24 + 0x81);
> 
> and it's pretty obvious why this causes an error.  Instead, try
> compiling:
> 
> unsigned int k = (0x80 << 24) + 0x81;
> 
> You may get an error message about signed-integer overflow, but not about
> shift-count overflow.
> 

Hi Alan,

Your analysis is correct, I did not check the warning message correctly.

Peter

  reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-16 10:16 [PATCH 0/3] usb: cdns3: three bug fixes for v5.10 Peter Chen
2020-10-16 10:16 ` [PATCH 1/3] usb: cdns3: gadget: suspicious implicit sign extension Peter Chen
2020-10-27  9:03   ` Felipe Balbi
2020-10-27  9:48     ` Peter Chen
2020-10-27 10:08       ` David Laight
2020-10-27 14:21       ` Alan Stern
2020-10-28  6:41         ` Peter Chen [this message]
2020-10-27  9:03   ` Felipe Balbi
2020-10-16 10:16 ` [PATCH 2/3] usb: cdns3: gadget: own the lock wrongly at the suspend routine Peter Chen
2020-10-27  9:08   ` Felipe Balbi
2020-10-27  9:08   ` Felipe Balbi
2020-10-16 10:16 ` [PATCH 3/3] usb: cdns3: Fix on-chip memory overflow issue Peter Chen
2020-10-27  9:11   ` Felipe Balbi

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