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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?TrgUp44y6oZ3SyPpeQfMfCFsHUS1CN1bLrwTnpHhkB71088SWy3tefUvaP10?= =?us-ascii?Q?QiNxr+v6BBXTUkO4kP866mb2C6EkxFbZgmiCTTSOQF9t9SrSRzwENrKnR25S?= =?us-ascii?Q?FwRBFpxNJ1iMBp10A7Aa/6TRJ2Dgr+8RDFqjkuFtFBPtnJyG+z9oPUeThK5U?= =?us-ascii?Q?KB+Fg1s4u4R7bpyMDGo+Nlr/baMM1xFVsEiIXat+GO0a6FtewRHABe6hGq0Z?= =?us-ascii?Q?I22YrJDcpA5A0eVkJGho0z+hwpqAavEvr2SDBcDKupMBkMKJPLCql0/O6yhR?= =?us-ascii?Q?w+ixRZKccRlCBZXRzWFyk3uAxjnYNKELPXG7MWwHarsqLGZcdaIsahb1COeo?= =?us-ascii?Q?22oG83seqIJQvqYgPep53bHgLfppt0cYf9R3p3pZNoPTaqM6i054gWPi1jf4?= =?us-ascii?Q?IxsVIvqn+ECT+yHdtY2lTrUdWGudJK4rJYGyy0+06A061uSPQmAVe/OGfhVU?= =?us-ascii?Q?Ph72Bcbw7eOLbv4ooqrSmRtcmPecQIQQYF1jmwlZOu9caOcAuURo4z4WbX3+?= =?us-ascii?Q?brN37uvCO8HRCFHfnbuftM7pFKJopFUow1NTUuDEDpRVZ9ZBntWb+uSdyO83?= =?us-ascii?Q?kui9FQAM4vRAuWnHTXS0zf8kXZBjKES9JdKaRX8AUSOIxBkB/B2OQakUziC1?= =?us-ascii?Q?tMoBs47ZYIvkRwWx9bM7/Jnwo05PvhkJFHWNf7iKl5pBTb5xfdQFk4eUaCNY?= =?us-ascii?Q?LJU0Bsc9eD69XnAo+SnX1KCyxzIsfJK/7sDrQFoM3wj/aCJXcTypHrKsSyDF?= =?us-ascii?Q?mVVJftTefBF0nPKa84a1ERDAuylrUjq3Q1gaHCpb2o16lgLJlLBH4aIm7cma?= =?us-ascii?Q?hLtksMaHO4DpQsxqq0Bk9vE3kH7MyrfLcH/3t5d0aVwVlIwuxiddPOOEJgYQ?= =?us-ascii?Q?66DlX1It3a3cpvN5QwrU2Aok5BiOfdUquAY5aCaHfTl2WDgl9Ww6kifHYGYb?= =?us-ascii?Q?E+ijOYomaJloVCPfl/R/lcdpsZkY+2sxIjUH8twd/AV22piZ/r5uXew/+YHD?= =?us-ascii?Q?x4zRscc1Y45hfOr+i2RhcfqcMBnleM5Ckm/gtevPEluotb1Fn7zIKVmksEyV?= =?us-ascii?Q?D7rRBIyAscr6fDeh3ZM6HfTT1BGc1/hfDsZ3sQxecz+4hHoX6kNu9NUf9Msj?= =?us-ascii?Q?ZVqRSdebuhLOnPO4gT5+/Hsxl8ss8NBO68pay6Y6NL/QaMpmWjUixP2LhAu+?= =?us-ascii?Q?zRoRiOIgMY1mw/HUE1cXuosj3BHV5CYUqiSCVcIAApSNRJLB5ao+tqJKu9Bm?= =?us-ascii?Q?URHonuIMnRnYgs8Y5QdgNt3HC66QI/z+kgcbmL2z6VVgAv61W56pcW0+aFxl?= =?us-ascii?Q?xlohVkEnO9wOSlxdIG1y8MofUFUnGUMO86ajgMLF414OQHx7700+blyEgDnP?= =?us-ascii?Q?ZGtinhWLGnS5+dJ6jwDrnyCLm+/IMGtLdnICFDQfGlxd92F6iNnhueeB4Oqs?= =?us-ascii?Q?HQQ8zhoHDh6NrLqupj2wVACZKEo+O7OZ5qDUc5YLXb7nBYwfICWvfXsM/dQq?= =?us-ascii?Q?UHlGNPVjipfarpdvNrfKXlfXcG7BD+TebfJZBNA/ZmXsJeTQYVvtEvQvXhsc?= =?us-ascii?Q?uWuzbGZhTicndbT5RoZ+xx9LYJ5KaFyv/6NfcX5g?= X-MS-Exchange-CrossTenant-Network-Message-Id: c04d5935-eb86-45a6-fcbc-08db048a0248 X-MS-Exchange-CrossTenant-AuthSource: SA1PR11MB6733.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Feb 2023 19:24:59.5736 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: KkhmShSondnzHS+EbgdDVkAi/7C6m/eKVK50YKoctsLwwpUj56vAjDJqjRWMowj58Lm9rpiLb+PUoDiiPY/NzQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR11MB4567 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org Davidlohr Bueso wrote: > On Tue, 31 Jan 2023, Dan Williams wrote: > > >Ira Weiny wrote: > >[..] > >> > Considering MSIs are edge triggered interrupts, this should be benign. > >> > >> I'm trying to understand this a bit more. So I looked in more detail. I > >> believe Dan suggested that I could use irq_default_primary_handler() in > >> this case by passing NULL. And this would handle threading the irq > >> processing for me. > >> > >> It looks from a software standpoint this should work. But the kdocs > >> really imply that not masking the irq in the handler may be an issue. > >> Thus the 'requirement' of using IRQF_ONESHOT. > >> > >> Is this somehow different with MSI? Is this a case of the kdocs being a > >> bit out of date for MSI? > > > >My reading, may be from the changelog and not the kdocs, was that at > >request_irq() time it is difficult to discern level triggered vs > >edge-triggered. So for the default primary handler, that does nothing to > >quiet a screaming level-triggered interrupt, just require oneshot mode. > > Right and it's only level-triggered that are the problem after done with > the hardirq handler. So in the msi/cxl case we already know that all this > is edge (sent once and forgotten by the hardware), which is why I was saying > it's harmless. It's still probably a good idea to have it explicitly oneshot > semantics as Dan's patch. Ok that makes sense. Thanks to you both for clarifying and to Dan for the patch. Ira