From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 667581CA8E for ; Fri, 26 Jan 2024 14:35:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706279712; cv=none; b=fVsw7xinf4rbeWls4B/pICmj5xy0187uz+liYSladLrgpitkPvYp+g+APZTQ9voNvCLTr6WJq+B45mA6/vX74K0BtRQZAjwJ9piY0H3dAvyjhruzDyIS4N+jIrBTauLO7NnaK+y43ozp/iCFXlzj5oamUCe7aI2BpKn0tnFznDQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706279712; c=relaxed/simple; bh=5Mp8HJAIqERvQL0b3/83tZjCcwW56ouo++Tx5D+tlFg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=EVLcpTzoL5lzHQhbVm+qaMVx3pHEFP0WhwTcbPjmYH6fXDvNtfHM40zAURNYhVgt6nZo9ROezADNYYzPuRqcEPM36ddxolXe36tjObR/mMjEcEOBYUhIQAkYEHsiTVDml8YlXeUV4p7PNOBEGgj6I88bovJT9yDNUKLN7HCQikY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=OclmvU6G; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="OclmvU6G" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1706279710; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Gu8a9U+kDXaRGvEtVtRt5Sa1+ew9Z1jeQJa10E23ijo=; b=OclmvU6GzPGzRwit2i4GqrnrLMnJAnqGgov8+GBXPgLhNwynTKeF6R5F20SikRFBcZ5IyN pcIOmUTRFS6cJTaFzVgxEQPIV89OceQuyoBNyjAppZgelkAbbI7RzPLYZ/Xo8MduF/PcWS ijtR/wcIb/M5PFG4AweiiJS/dtVRLqo= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-567-6a8axaRlOeC6WIXbPx2xyQ-1; Fri, 26 Jan 2024 09:35:06 -0500 X-MC-Unique: 6a8axaRlOeC6WIXbPx2xyQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EDEB82825BAC; Fri, 26 Jan 2024 14:35:05 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.164]) by smtp.corp.redhat.com (Postfix) with SMTP id 4E0802028CD2; Fri, 26 Jan 2024 14:35:04 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 26 Jan 2024 15:33:52 +0100 (CET) Date: Fri, 26 Jan 2024 15:33:50 +0100 From: Oleg Nesterov To: Christian Brauner Cc: Tycho Andersen , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Tycho Andersen , "Eric W. Biederman" Subject: Re: [PATCH v3 1/3] pidfd: allow pidfd_open() on non-thread-group leaders Message-ID: <20240126143349.GD7386@redhat.com> References: <20240123153452.170866-1-tycho@tycho.pizza> <20240123153452.170866-2-tycho@tycho.pizza> <20240123195608.GB9978@redhat.com> <20240125140830.GA5513@redhat.com> <20240126-kulinarisch-ausziehen-d2af51882d2f@brauner> Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240126-kulinarisch-ausziehen-d2af51882d2f@brauner> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 On 01/26, Christian Brauner wrote: > > > --- a/include/uapi/linux/pidfd.h > > +++ b/include/uapi/linux/pidfd.h > > @@ -7,6 +7,7 @@ > > #include > > > > /* Flags for pidfd_open(). */ > > -#define PIDFD_NONBLOCK O_NONBLOCK > > +#define PIDFD_NONBLOCK O_NONBLOCK > > +#define PIDFD_THREAD O_EXCL // or anything else not used by anon_inode's > > I like it! > > The only request I would have is to not alias O_EXCL and PIDFD_THREAD. > Because it doesn't map as clearly as NONBLOCK did. But it would be nice to have PIDFD_THREAD in file->f_flags. Where else can we keep it? I chose O_EXCL because it can only be used at open time, it can never be used or changed after anon_inode_getfile(), so we can safely do pidfd_file->f_flags |= PIDFD_THREAD; in __pidfd_prepare() and then check in pidfd_poll/pidfd_send_signal. What do you suggest instead? Oleg.