From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from dgate20.ts.fujitsu.com ([80.70.172.51]:65393 "EHLO dgate20.ts.fujitsu.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755902Ab3CNRbk (ORCPT ); Thu, 14 Mar 2013 13:31:40 -0400 Message-Id: <61eb00$3h5801@dgate20u.abg.fsc.net> Date: 14 Mar 2013 18:31:39 +0100 From: Bodo Stroesser To: neilb@suse.de Cc: bfields@fieldses.org, linux-nfs@vger.kernel.org, bstroesser@ts.fujitsu.com Subject: Re: sunrpc/cache.c: races while updating cache entries Content-Type: text/plain; charset=us-ascii Sender: linux-nfs-owner@vger.kernel.org List-ID: T24gMTMgTWFyIDIwMTMgMDc6NTU6MDAgKzAxMDAgTmVpbEJyb3duIDxuZWlsYkBzdXNlLmRl PiB3cm90ZToKCj4gT24gMTEgTWFyIDIwMTMgMTc6MTM6NDEgKzAxMDAgQm9kbyBTdHJvZXNz ZXIgPGJzdHJvZXNzZXJAdHMuZnVqaXRzdS5jb20+Cj4gd3JvdGU6Cj4gCj4gPiBIaSwKPiA+ IAo+ID4gQUZBSUNTLCB0aGVyZSBpcyBvbmUgbW9yZSByYWNlIGluIFJQQyBjYWNoZS4KPiA+ IAo+ID4gVGhlIHByb2JsZW0gc2hvd2VkIHVwIGZvciB0aGUgImF1dGgudW5peC5pcCIgY2Fj aGUsIHRoYXQKPiA+IGhhcyBhIHJlYWRlci4KPiA+IAo+ID4gSWYgYSBzZXJ2ZXIgdGhyZWFk IHRyaWVzIHRvIGZpbmQgYSBjYWNoZSBlbnRyeSwgaXQgZmlyc3QKPiA+IGRvZXMgYSBsb29r dXAgKG9yIGNhbGxzIGlwX21hcF9jYWNoZWRfZ2V0KCkgaW4gdGhpcyBzcGVjaWZpYwo+ID4g Y2FzZSkuIFRoZW4sIGl0IGNhbGxzIGNhY2hlX2NoZWNrKCkgZm9yIHRoaXMgZW50cnkuCj4g PiAKPiA+IElmIHRoZSByZWFkZXIgdXBkYXRlcyB0aGUgY2FjaGUgZW50cnkganVzdCBiZXR3 ZWVuIHRoZQo+ID4gdGhyZWFkJ3MgbG9va3VwIGFuZCBjYWNoZV9jaGVjaygpIGV4ZWN1dGlv biwgY2FjaGVfY2hlY2soKQo+ID4gd2lsbCBkbyBhbiB1cGNhbGwgZm9yIHRoaXMgY2FjaGUg ZW50cnkuIFRoaXMgaXMsIGJlY2F1c2UKPiA+IHN1bnJwY19jYWNoZV91cGRhdGUoKSBjYWxs cyBjYWNoZV9mcmVzaF9sb2NrZWQob2xkLCAwKSwKPiA+IHdoaWNoIHNldHMgZXhwaXJ5X3Rp bWUgdG8gMC4KPiA+IAo+ID4gVW5mb3J0dW5hdGVseSwgdGhlIHJlcGx5IHRvIHRoZSB1cGNh bGwgd2lsbCBub3QgZGVxdWV1ZQo+ID4gdGhlIHF1ZXVlZCBjYWNoZV9yZXF1ZXN0LCBhcyB0 aGUgcmVwbHkgd2lsbCBiZSBhc3NpZ25lZCB0bwo+ID4gdGhlIGNhY2hlIGVudHJ5IG5ld2x5 IGNyZWF0ZWQgYnkgdGhlIGFib3ZlIGNhY2hlIHVwZGF0ZS4KPiA+IAo+ID4gVGhlIHJlc3Vs dCBpcyBhIGdyb3dpbmcgcXVldWUgb2Ygb3JwaGFuZWQgY2FjaGVfcmVxdWVzdAo+ID4gc3Ry dWN0dXJlcyAtLT4gbWVtb3J5IGxlYWsuCj4gPiAKPiA+IEkgZm91bmQgdGhpcyBvbiBhIFNM RVMxMSBTUDEgd2l0aCBhIGJhY2twb3J0IG9mIHRoZSBsYXRlc3QKPiA+IHBhdGNoZXMgdGhh dCBmaXggdGhlIG90aGVyIFJQQyByYWNlcy4gT24gdGhpcyBvbGQga2VybmVsLAo+ID4gdGhl IHByb2JsZW0gYWxzbyBsZWFkcyB0byBzdmNfZHJvcCgpIGJlaW5nIGNhbGxlZCBmb3IgdGhl Cj4gPiBhZmZlY3RlZCBSUEMgcmVxdWVzdCAoYWZ0ZXIgc3ZjX2RlZmVyKCkpLgo+ID4gCj4g PiBCZXN0IFJlZ2FyZHMKPiA+IEJvZG8KPiAKPiBJIGRvbid0IHRoaW5rIHRoaXMgaXMgYSBy ZWFsIHByb2JsZW0uCj4gVGhlIHBlcmlvZGljIGNhbGwgdG8gImNhY2hlX2NsZWFuIiBzaG91 bGQgZmluZCB0aGVzZSBvcnBoYW5lZCByZXF1ZXN0cyBhbmQKPiBwdXJnZSB0aGVtLiAgU28g eW91IGNvdWxkIGdldCBhIHNob3J0IHRlcm0gbWVtb3J5IGxlYWssIGJ1dCBpdCBzaG91bGQK PiBjb3JyZWN0IGl0c2VsZi4KPiBEbyB5b3UgYWdyZWU/Cj4gCj4gVGhhbmtzLAo+IE5laWxC cm93bgoKTWVhbndoaWxlIEkgZm91bmQgdGhlIG1pc3NpbmcgcGFydCBvZiB0aGUgcmFjZSEK Ckl0J3MganVzdCB3aGF0IEkgd3JvdGUgYWJvdmUgYnV0IGFkZGl0aW9uYWxseSwgaW1tZWRp YXRlbHkgYWZ0ZXIKdGhlIHJlYWRlciB1cGRhdGVkIHRoZSBjYWNoZSwgY2FjaGVfY2xlYW4o KSB1bmhhc2hlcyB0aGUgb2xkIGNhY2hlCmVudHJ5LiBJbiB0aGF0IGNhc2U6CjEpIHRoZSB0 aHJlYWQgd2lsbCBxdWV1ZSBhIHJlcXVlc3QgZm9yIGEgY2FjaGUgZW50cnksIHRoYXQgaXNu J3QKICAgaW4gdGhlIGhhc2ggbGlzdHMuCjIpIGNhY2hlX2NsZWFuKCkgbmV2ZXIgd2lsbCBh Y2Nlc3MgdGhpcyBvbGQgY2FjaGUgZW50cnkgYWdhaW4KMykgZXZlcnkgZnVydGhlciBjYWNo ZSB1cGRhdGUgd2lsbCBjYWxsIGNhY2hlX2RlcXVldWUoKSBmb3IgYSBuZXdlcgogICBjYWNo ZSBlbnRyeSwgdGhlIHJlcXVlc3QgaXMgbmV2ZXIgZGVxdWV1ZWQKCi0tPiBtZW1vcnkgbGVh ay4KCkkgdmVyaWZpZWQgdGhpcyBpbnNlcnRpbmcgc29tZSBkZWJ1ZyBpbnN0cnVjdGlvbnMu IEluIGEgdGVzdHJ1bgp0aGF0IHRyaWdnZXJlZCA2IHRpbWVzLCBhbmQgdGhlIHF1ZXVlIHBy aW50ZWQgYnkgY3Jhc2ggYWZ0ZXIgdGhlCnJ1biBoYWQgNiBvcnBoYW5lZCBlbnRyaWVzLgoK QXMgSSB3cm90ZSB5ZXN0ZXJkYXksIEkgaGF2ZSBhIHBhdGNoIHRoYXQgc29sdmVzIHRoZSBw cm9ibGVtIGJ5CnJldGVzdGluZyB0aGUgc3RhdGUgb2YgdGhlIGNhY2hlIGVudHJ5IGFmdGVy IHNldHRpbmcgQ0FDSEVfUEVORElORwppbiBjYWNoZV9jaGVjaygpLiBJIGNhbiBzZW5kIGl0 IGlmIHlvdSBsaWtlLgoKQm9kbwoKUC5TLjoKTWF5YmUgSSdtIHdyb25nLCBidXQgQUZBSUNT LCB0aGVyZSBhcmUgdHdvIGZ1cnRoZXIgbWlub3IgcHJvYmxlbXMKcmVnYXJkaW5nIChuZWFy bHkpIGV4cGlyZWQgY2FjaGUgZW50cmllczoKYSkgaXBfbWFwX2NhY2hlZF9nZXQoKSBpbiBz b21lIHNpdHVhdGlvbnMgY2FuIHJldHVybiBhbiBhbHJlYWR5CiAgIG91dGRhdGVkIChpdCB1 c2VzIGNhY2hlX3ZhbGlkIHRoYXQgbm90IGZ1bGx5IGNoZWNrcyB0aGUgc3RhdGUpCiAgIGNh Y2hlIGVudHJ5LiBJZiBjYWNoZV9jaGVjaygpIGlzIGNhY2xsZWQgZm9yIHRoYXQgZW50cnks IGl0IHdpbGwKICAgZmFpbCwgSSB0aGluawpiKSBHZW5lcmFsbHksIGlmIGEgY2FjaGUgZW50 cnkgaXMgcmV0dXJuZWQgYnkgc3VucnBjX2NhY2hlX2xvb2t1cCgpCiAgIGFuZCB0aGUgZW50 cnkgaXMgaW4gdGhlIGxhc3Qgc2Vjb25kIG9mIGl0J3MgZXhwaXJ5X3RpbWUsIHRoZSAKICAg Y2xvY2sgbWlnaHQgbW92ZSB0byB0aGUgbmV4dCBzZWNvbmQgYmVmb3JlIGNhY2hlX2NoZWNr IGlzIGNhbGxlZC4KICAgSWYgdGhpcyBoYXBwZW5zLCBjYWNoZV9jaGVjayB3aWxsIGZhaWws IEkgdGhpbmsuCkRvIHlvdSBhZ3JlZT8K