Hi David and Jan, I did more testing on the code. Casting to either (long) or (unsigned long) would be fine.
However, there is still an issue that ref is of type uint32_t and IS_ERR_VALUE((unsigned long)ref) would not return true when ref=-ENOSPC (or other error code). IS_ERR_VALUE((long)ref) would return false as well. The solution is to cast ref to (int) first as follows: - BUG_ON((signed short)ref < 0); + WARN_ON_ONCE(IS_ERR_VALUE((unsigned long)(int)ref)); David, I am very sorry for this error and I will be careful the next time. Would you please let me know if I should resend a new patch or an incremental based on previous one at https://git.kernel.org/cgit/linux/kernel/git/davem/net.git? Thank you very much! Dongli Zhang ----- Original Message ----- From: da...@davemloft.net To: dongli.zh...@oracle.com Cc: linux-kernel@vger.kernel.org, xen-de...@lists.xenproject.org, net...@vger.kernel.org, boris.ostrov...@oracle.com, david.vra...@citrix.com, jgr...@suse.com Sent: Tuesday, November 1, 2016 4:06:27 AM GMT +08:00 Beijing / Chongqing / Hong Kong / Urumqi Subject: Re: [PATCH 1/1] xen-netfront: do not cast grant table reference to signed short From: Dongli Zhang <dongli.zh...@oracle.com> Date: Mon, 31 Oct 2016 13:38:29 +0800 > While grant reference is of type uint32_t, xen-netfront erroneously casts > it to signed short in BUG_ON(). > > This would lead to the xen domU panic during boot-up or migration when it > is attached with lots of paravirtual devices. > > Signed-off-by: Dongli Zhang <dongli.zh...@oracle.com> Since this is consistent with how the macros in linux/err.h handle "is this an error" checks, this change looks good to me. Applied, thanks.
