From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: Deadlock in /proc/xen/xenbus watch+read on 3.17+ (maybe earlier) Date: Thu, 19 Mar 2015 10:38:32 +0000 Message-ID: <1426761512.610.18.camel@citrix.com> References: <20150319011911.GA29029@mail-itl> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <20150319011911.GA29029@mail-itl> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Marek =?ISO-8859-1?Q?Marczykowski-G=F3recki?= Cc: Iurii Konovalenko , Embedded-pv-devel@lists.xenproject.org, Boris Ostrovsky , David Vrabel , xen-devel List-Id: xen-devel@lists.xenproject.org T24gVGh1LCAyMDE1LTAzLTE5IGF0IDAyOjE5ICswMTAwLCBNYXJlayBNYXJjenlrb3dza2ktR8Oz cmVja2kgd3JvdGU6Cj4gSGksCj4gCj4gSSd2ZSBoaXQgc29tZSBkZWFkbG9jayBpbiBrZXJuZWwg eGVuc3RvcmUgY2xpZW50IGV4cG9zZWQgdmlhCj4gL3Byb2MveGVuL3hlbmJ1cy4KClNvdW5kcyBz aW1pbGFyIHRvIHdoYXQgSXVyaWkgYWxzbyByZXBvcnRlZCBsYXN0IG5pZ2h0IGluICJVc2Vyc3Bh Y2UgUFYKYmFja2VuZCBoYW5ncyIuCgpJdXJyaSdzIGNhc2Ugd2FzIGFsbCAzLjE0IGtlcm5lbHMs IHdoaWNoIGlzIGluIHlvdXIgcmFuZ2UgdG9vLgoKPiAgU3RlcHMgdG8gcmVwcm9kdWNlIGFyZSBz aW1wbGU6Cj4gaW50IG1haW4oKSB7Cj4gCXN0cnVjdCB4c19oYW5kbGUgKnhzOwo+IAl4cyA9IHhz X29wZW4oMCk7Cj4gCXhzX3dhdGNoKHhzLCAiZG9taWQiLCAidG9rZW4iKTsKPiAJeHNfcmVhZCh4 cywgMCwgIm5hbWUiLCBOVUxMKTsKPiAJcmV0dXJuIDA7Cj4gfQo+IAo+IHhzX3dhdGNoIGludGVy bmFsbHkgY3JlYXRlcyBuZXcgdGhyZWFkLCB3aGljaCB1c2VzIHJlYWQgdG8gd2FpdCBmb3IgdGhl Cj4gd2F0Y2guIEFuZCBpbiB0aGUgc2FtZSB0aW1lLCB0aGUgcHJvZ3JhbSB0cmllcyB0byByZWFk IHNvbWUgdmFsdWUsCj4gYnV0IGFjdHVhbGx5IGl0IGhhbmdzIGF0IHNlbmRpbmcgdGhlIGNvbW1h bmQgKGJlZm9yZSBldmVuIHNlbmRpbmcgYSBwYXRoIHRvIGJlCj4gcmVhZCkuIFN0cmFjZSBnaXZl cyB0aGlzIChzaW1wbGlmaWVkIGZvciByZWFkYWJpbGl0eSk6Cj4gW3BpZCAgMjQ5NF0gd3JpdGUo MywgIlw0XDBcMFwwXDBcMFwwXDBcMFwwXDBcMFxmXDBcMFwwIiwgMTYwID0gMTYKPiBbcGlkICAy NDk0XSB3cml0ZSgzLCAiZG9taWRcMCIsIDYpICAgICAgPSA2Cj4gW3BpZCAgMjQ5NF0gd3JpdGUo MywgInRva2VuXDAiLCA2KSAgICAgID0gNgo+IFtwaWQgIDI0OTVdIHJlYWQoMywgIDx1bmZpbmlz aGVkIC4uLj4KPiBbcGlkICAyNDk0XSBmdXRleCgweDcxYzBkNCwgRlVURVhfV0FJVF9QUklWQVRF LCAxLCBOVUxMIDx1bmZpbmlzaGVkIC4uLj4KPiBbcGlkICAyNDk1XSA8Li4uIHJlYWQgcmVzdW1l ZD4KPiAiXDE3XDBcMFwwXDM3N1wzNzdcMzc3XDM3N1wyMjB+XDI1NVwyN1xmXDBcMFwwIiwgMTYp ID0gMTYKPiBbcGlkICAyNDk1XSByZWFkKDMsICJkb21pZFwwdG9rZW5cMCIsIDEyKSA9IDEyCj4g W3BpZCAgMjQ5NV0gcmVhZCgzLCAiXDRcMFwwXDBcMFwwXDBcMFwwXDBcMFwwXDNcMFwwXDAiLCAx NikgPSAxNgo+IFtwaWQgIDI0OTVdIHJlYWQoMywgIk9LXDAiLCAzKSAgICAgICAgICA9IDMKPiBb cGlkICAyNDk1XSBmdXRleCgweDcxYzBkNCwgRlVURVhfV0FLRV9PUF9QUklWQVRFLCAxLCAxLCAw eDcxYzBkMCwKPiB7RlVURVhfT1BfU0VULCAwLCBGVVRFWF9PUF9DTVBfR1QsIDF9IDx1bmZpbmlz aGVkIC4uLj4KPiBbcGlkICAyNDk0XSA8Li4uIGZ1dGV4IHJlc3VtZWQ+ICkgICAgICAgPSAwCj4g W3BpZCAgMjQ5NV0gPC4uLiBmdXRleCByZXN1bWVkPiApICAgICAgID0gMQo+IFtwaWQgIDI0OTRd IGZ1dGV4KDB4NzFjMGE4LCBGVVRFWF9XQUlUX1BSSVZBVEUsIDIsIE5VTEwgPHVuZmluaXNoZWQg Li4uPgo+IFtwaWQgIDI0OTVdIGZ1dGV4KDB4NzFjMGE4LCBGVVRFWF9XQUtFX1BSSVZBVEUsIDEg PHVuZmluaXNoZWQgLi4uPgo+IFtwaWQgIDI0OTRdIDwuLi4gZnV0ZXggcmVzdW1lZD4gKSAgICAg ICA9IC0xIEVBR0FJTiAoUmVzb3VyY2UKPiB0ZW1wb3JhcmlseSB1bmF2YWlsYWJsZSkKPiBbcGlk ICAyNDk1XSA8Li4uIGZ1dGV4IHJlc3VtZWQ+ICkgICAgICAgPSAwCj4gW3BpZCAgMjQ5NF0gZnV0 ZXgoMHg3MWMwYTgsIEZVVEVYX1dBS0VfUFJJVkFURSwgMSA8dW5maW5pc2hlZCAuLi4+Cj4gW3Bp ZCAgMjQ5NV0gcmVhZCgzLCAgPHVuZmluaXNoZWQgLi4uPgo+IFtwaWQgIDI0OTRdIDwuLi4gZnV0 ZXggcmVzdW1lZD4gKSAgICAgICA9IDAKPiBbcGlkICAyNDk0XSBydF9zaWdhY3Rpb24oU0lHUElQ RSwge1NJR19ERkwsIFtdLCBTQV9SRVNUT1JFUiwKPiAweDdmYzc4YzE0ODhmMH0sIE5VTEwsIDgp ID0gMAo+IFtwaWQgIDI0OTRdIHJ0X3NpZ2FjdGlvbihTSUdQSVBFLCB7U0lHX0lHTiwgW10sIFNB X1JFU1RPUkVSLAo+IDB4N2ZjNzhjMTQ4OGYwfSwge1NJR19ERkwsIFtdLCBTQV9SRVNUT1JFUiwg MHg3ZmM3OGMxNDg4ZjB9LCA4KSA9IDAKPiBbcGlkICAyNDk0XSB3cml0ZSgzLCAiXDJcMFwwXDBc MFwwXDBcMFwwXDBcMFwwXDVcMFwwXDAiLCAxNgo+IAo+IEFuZCB0aGF0cyBhbGwgLSAyNDk0IGlz IHdhaXRpbmcgb24gd3JpdGUsIDI0OTUgaXMgd2FpdGluZyBvbiByZWFkLgo+IAo+IE9uIDMuMTIu eCBpdCBpcyB3b3JraW5nLiBPbiAzLjE3LjAgYW5kIDMuMTguNyBpdCBpcyBicm9rZW4uIEkgaGF2 ZW4ndAo+IGNoZWNrZWQgdmVyc2lvbnMgaW4gdGhlIG1pZGRsZS4KPiAKPiBBbnkgaWRlYXM/Cj4g Cj4gX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KPiBYZW4t ZGV2ZWwgbWFpbGluZyBsaXN0Cj4gWGVuLWRldmVsQGxpc3RzLnhlbi5vcmcKPiBodHRwOi8vbGlz dHMueGVuLm9yZy94ZW4tZGV2ZWwKCgoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX18KWGVuLWRldmVsIG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVu Lm9yZwpodHRwOi8vbGlzdHMueGVuLm9yZy94ZW4tZGV2ZWwK