lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 28 Oct 2010 13:27:14 -0700 From: "Nicholas A. Bellinger" <nab@...ux-iscsi.org> To: Boaz Harrosh <bharrosh@...asas.com> Cc: Andi Kleen <ak@...ux.intel.com>, James Bottomley <James.Bottomley@...e.de>, Mike Anderson <andmike@...ux.vnet.ibm.com>, linux-kernel <linux-kernel@...r.kernel.org>, linux-scsi <linux-scsi@...r.kernel.org>, Vasu Dev <vasu.dev@...ux.intel.com>, Tim Chen <tim.c.chen@...ux.intel.com>, Matthew Wilcox <willy@...ux.intel.com>, Mike Christie <michaelc@...wisc.edu>, Jens Axboe <jaxboe@...ionio.com>, James Smart <james.smart@...lex.com>, Andrew Vasquez <andrew.vasquez@...gic.com>, FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>, Hannes Reinecke <hare@...e.de>, Joe Eykholt <jeykholt@...co.com>, Christoph Hellwig <hch@....de>, Jon Hawley <warthog9@...nel.org>, Brian King <brking@...ux.vnet.ibm.com>, Christof Schmitt <christof.schmitt@...ibm.com>, Tejun Heo <tj@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, "H. Peter Anvin" <hpa@...or.com>, julia@...u.dk Subject: Re: [ANNOUNCE] Status of unlocked_qcmds=1 operation for .37 On Thu, 2010-10-28 at 13:18 +0200, Boaz Harrosh wrote: > On 10/28/2010 11:10 AM, Andi Kleen wrote: > > On Wed, Oct 27, 2010 at 09:27:38AM -0500, James Bottomley wrote: > >> On Wed, 2010-10-27 at 09:53 +0200, Andi Kleen wrote: > >>>> This sounds like a pretty reasonable compromise that I think is slightly > >>>> less risky for the LLDs with the ghosts and cob-webs hanging off of > >>>> them. > >>> > >>> They won't get tested either next release cycle. Essentially > >>> near nobody uses them. > >>> > >>>> > >>>> What do you think..? > >>> > >>> Standard linux practice is to simply push the locks down. That's a pretty > >>> mechanical operation and shouldn't be too risky > >>> > >>> With some luck you could even do it with coccinelle. > >> > >> Precisely ... if we can do the push down now as a mechanical > >> transformation we can put it in the current merge window as a low risk > >> API change. This gives us optimal exposure to the rc sequence to sort > >> out any problems that arise (or drivers that got missed) with the lowest > >> risk of such problems actually arising. Given the corner cases and the > >> late arrival of fixes, the serial number changes are just too risky for > >> the current merge window. Having an API that changes depending on a > >> flag is also a high risk process because it's prone to further sources > >> of error. > > > > Here's a coccinelle script I came up with that does the push down. > > It still adds a bogus empty line in front of the irqflags declaration > > which I haven't managed to avoid yet. Other than the it seems > > to DTRT on the SCSI drivers I tried. > > > > -Andi > > > > > > @ rule1 @ > > struct scsi_host_template t; > > identifier qc; > > @@ > > t.queuecommand = qc; > > > > @ rule2 @ > > identifier rule1.qc; > > identifier cmnd; > > expression E; > > statement S, S2; > > @@ > > int qc(struct scsi_cmnd *cmnd, ...) > > { > > ... when != S > > + unsigned long irqflags; > > > > + spin_lock_irqsave(&cmnd->device->host->hostlock, irqflags); > > S2 > > ... > > + spin_unlock_irqrestore(&cmnd->device->host->hostlock, irqflags); > > return E; > > } > > > > I disagree with your approach this introduces a spin_unlock_irqrestore > call site at every return, in the usually huge queuecommand. > > I'd say just do: > - Rename XXX_queuecommand => __XXX_queuecommand_unlocked > - Define new XXX_queuecommand > > int qc(struct scsi_cmnd *cmnd, ...) > { > unsigned long irqflags; > int ret; > > spin_lock_irqsave(&cmnd->device->host->hostlock, irqflags); > ret = __XXX_queuecommand_unlocked(cmnd, ...) > spin_unlock_irqrestore(&cmnd->device->host->hostlock, irqflags); > return ret; > } > > Then when the driver is manually converted the __queuecommand_unlocked > can be set into the scsi_host_template and the added function can > be dropped. > I would have to agree that approach does make a bit more sense.. Now can some brave soul (/me looks at ak) code another script to automate this for the identified legacy LLDs cases that need push down..? 8-) --nab -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists