From: Ira Weiny <ira.weiny@intel.com>
To: Alison Schofield <alison.schofield@intel.com>,
Ira Weiny <ira.weiny@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>, Fan Ni <fan.ni@samsung.com>,
"Jonathan Cameron" <Jonathan.Cameron@huawei.com>,
Navneet Singh <navneet.singh@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Vishal Verma <vishal.l.verma@intel.com>,
<linux-btrfs@vger.kernel.org>, <linux-cxl@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 05/26] cxl/core: Simplify cxl_dpa_set_mode()
Date: Fri, 3 May 2024 12:09:27 -0700 [thread overview]
Message-ID: <6635366717079_e1f582941d@iweiny-mobl.notmuch> (raw)
In-Reply-To: <ZhSPHvoTHl28GXt1@aschofie-mobl2>
Alison Schofield wrote:
> On Sun, Mar 24, 2024 at 04:18:08PM -0700, Ira Weiny wrote:
> > cxl_dpa_set_mode() checks the mode for validity two times, once outside
> > of the DPA RW semaphore and again within.
>
> Not true.
Sorry for not being clear. It does check the mode 2x but not for
validity. I'll clarify.
> It only checks mode once before the lock. It checks for
> capacity after the lock. If it didn't check mode before the lock,
> then unsupported modes would fall through.
But we can check the mode 1 time and either check the size or fail.
>
> > The function is not in a critical path.
>
> Implying what here? OK to check twice (even though it wasn't)
> or OK to expand scope of locking.
Implying that checking the mode outside the lock is not required.
>
> > Prior to Dynamic Capacity the extra check was not much
> > of an issue. The addition of DC modes increases the complexity of
> > the check.
> >
> > Simplify the mode check before adding the more complex DC modes.
> >
>
> The addition of the DC mode check doesn't seem complex.
It is if you have to check it 2 times.
>
> Pardon my picking at the words, but if you'd like to refactor the
> function, just say so. The final result is a bit more readable, but
> also adding the DC mode checks without refactoring would read fine
> also.
When I added the DC mode to this function without this refactoring it was
quite a bit more code and ugly IMO. So this cleanup helped. If I were
not adding the DC code there would be much less reason to change this
function.
[snip]
> > diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> > index 7d97790b893d..66b8419fd0c3 100644
> > --- a/drivers/cxl/core/hdm.c
> > +++ b/drivers/cxl/core/hdm.c
> > @@ -411,44 +411,35 @@ int cxl_dpa_set_mode(struct cxl_endpoint_decoder *cxled,
> > struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> > struct cxl_dev_state *cxlds = cxlmd->cxlds;
> > struct device *dev = &cxled->cxld.dev;
> > - int rc;
> >
> > + guard(rwsem_write)(&cxl_dpa_rwsem);
> > + if (cxled->cxld.flags & CXL_DECODER_F_ENABLE)
> > + return -EBUSY;
> > +
> > + /*
> > + * Check that the mode is supported by the current partition
> > + * configuration
> > + */
> > switch (mode) {
> > case CXL_DECODER_RAM:
> > + if (!resource_size(&cxlds->ram_res)) {
> > + dev_dbg(dev, "no available ram capacity\n");
> > + return -ENXIO;
> > + }
> > + break;
> > case CXL_DECODER_PMEM:
> > + if (!resource_size(&cxlds->pmem_res)) {
> > + dev_dbg(dev, "no available pmem capacity\n");
> > + return -ENXIO;
> > + }
> > break;
> > default:
> > dev_dbg(dev, "unsupported mode: %d\n", mode);
> > return -EINVAL;
> > }
> >
>
> delete extra line
You don't like the space following the switch?
Ira
next prev parent reply other threads:[~2024-05-03 19:09 UTC|newest]
Thread overview: 160+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-24 23:18 [PATCH 00/26] DCD: Add support for Dynamic Capacity Devices (DCD) ira.weiny
2024-03-24 23:18 ` [PATCH 01/26] cxl/mbox: Flag " ira.weiny
2024-03-25 16:11 ` Jonathan Cameron
2024-03-25 22:16 ` fan
2024-03-25 22:56 ` Davidlohr Bueso
2024-04-02 22:26 ` Ira Weiny
2024-03-26 16:34 ` Dave Jiang
2024-04-02 22:30 ` Ira Weiny
2024-04-10 18:15 ` Alison Schofield
2024-03-24 23:18 ` [PATCH 02/26] cxl/core: Separate region mode from decoder mode ira.weiny
2024-03-25 16:20 ` Jonathan Cameron
2024-04-02 23:24 ` Ira Weiny
2024-03-25 23:18 ` Davidlohr Bueso
2024-03-28 5:22 ` Ira Weiny
2024-03-28 20:09 ` Dave Jiang
2024-04-02 23:27 ` Ira Weiny
2024-04-24 17:58 ` Ira Weiny
2024-04-02 23:25 ` Ira Weiny
2024-04-10 18:49 ` Alison Schofield
2024-03-24 23:18 ` [PATCH 03/26] cxl/mem: Read dynamic capacity configuration from the device ira.weiny
2024-03-25 17:40 ` Jonathan Cameron
2024-04-03 22:22 ` Ira Weiny
2024-03-25 23:36 ` fan
2024-04-03 22:41 ` Ira Weiny
2024-04-02 11:41 ` Jørgen Hansen
2024-04-05 18:09 ` Ira Weiny
2024-04-09 8:42 ` Jørgen Hansen
2024-04-09 2:00 ` Alison Schofield
2024-03-24 23:18 ` [PATCH 04/26] cxl/region: Add dynamic capacity decoder and region modes ira.weiny
2024-03-25 17:42 ` Jonathan Cameron
2024-03-26 16:17 ` fan
2024-03-27 15:43 ` Dave Jiang
2024-04-05 18:19 ` Ira Weiny
2024-04-06 0:01 ` Dave Jiang
2024-05-14 2:40 ` Zhijian Li (Fujitsu)
2024-03-24 23:18 ` [PATCH 05/26] cxl/core: Simplify cxl_dpa_set_mode() Ira Weiny
2024-03-25 17:46 ` Jonathan Cameron
2024-03-25 21:38 ` Davidlohr Bueso
2024-03-26 16:25 ` fan
2024-03-26 17:46 ` Dave Jiang
2024-04-05 19:21 ` Ira Weiny
2024-04-06 0:02 ` Dave Jiang
2024-04-09 0:43 ` Alison Schofield
2024-05-03 19:09 ` Ira Weiny [this message]
2024-05-03 20:33 ` Alison Schofield
2024-05-04 1:19 ` Dan Williams
2024-05-06 4:06 ` Ira Weiny
2024-05-04 4:13 ` Dan Williams
2024-05-06 3:46 ` Ira Weiny
2024-03-24 23:18 ` [PATCH 06/26] cxl/port: Add Dynamic Capacity mode support to endpoint decoders ira.weiny
2024-03-26 16:35 ` fan
2024-04-05 19:50 ` Ira Weiny
2024-03-26 17:58 ` Dave Jiang
2024-04-05 20:34 ` Ira Weiny
2024-04-04 8:32 ` Jonathan Cameron
2024-04-05 20:56 ` Ira Weiny
2024-05-06 16:22 ` Dan Williams
2024-05-10 5:31 ` Ira Weiny
2024-04-10 20:33 ` Alison Schofield
2024-03-24 23:18 ` [PATCH 07/26] cxl/port: Add dynamic capacity size " ira.weiny
2024-04-05 13:54 ` Jonathan Cameron
2024-05-03 17:09 ` Ira Weiny
2024-05-03 17:21 ` Dan Williams
2024-05-06 4:07 ` Ira Weiny
2024-04-10 22:50 ` Alison Schofield
2024-03-24 23:18 ` [PATCH 08/26] cxl/mem: Expose device dynamic capacity capabilities ira.weiny
2024-03-25 23:40 ` Davidlohr Bueso
2024-03-26 18:30 ` fan
2024-04-04 8:44 ` Jonathan Cameron
2024-04-04 8:51 ` Jonathan Cameron
2024-03-24 23:18 ` [PATCH 09/26] cxl/region: Add Dynamic Capacity CXL region support ira.weiny
2024-03-26 22:31 ` fan
2024-04-10 4:25 ` Ira Weiny
2024-03-27 17:27 ` Dave Jiang
2024-04-10 4:35 ` Ira Weiny
2024-04-04 10:26 ` Jonathan Cameron
2024-04-10 4:40 ` Ira Weiny
2024-03-24 23:18 ` [PATCH 10/26] cxl/events: Factor out event msgnum configuration Ira Weiny
2024-03-27 17:38 ` Dave Jiang
2024-04-04 15:07 ` Jonathan Cameron
2024-03-24 23:18 ` [PATCH 11/26] cxl/pci: Delay event buffer allocation Ira Weiny
2024-03-25 22:26 ` Davidlohr Bueso
2024-03-27 17:38 ` Dave Jiang
2024-04-04 15:08 ` Jonathan Cameron
2024-03-24 23:18 ` [PATCH 12/26] cxl/pci: Factor out interrupt policy check Ira Weiny
2024-03-27 17:41 ` Dave Jiang
2024-04-04 15:10 ` Jonathan Cameron
2024-03-24 23:18 ` [PATCH 13/26] cxl/mem: Configure dynamic capacity interrupts ira.weiny
2024-03-26 23:12 ` fan
2024-04-10 4:48 ` Ira Weiny
2024-03-27 17:54 ` Dave Jiang
2024-04-10 5:26 ` Ira Weiny
2024-04-04 15:22 ` Jonathan Cameron
2024-04-10 5:34 ` Ira Weiny
2024-04-10 23:23 ` Alison Schofield
2024-05-06 16:56 ` Dan Williams
2024-03-24 23:18 ` [PATCH 14/26] cxl/region: Read existing extents on region creation ira.weiny
2024-03-26 23:27 ` fan
2024-04-10 5:46 ` Ira Weiny
2024-03-27 17:45 ` fan
2024-04-10 6:19 ` Ira Weiny
2024-03-27 18:31 ` Dave Jiang
2024-04-10 6:09 ` Ira Weiny
2024-04-02 13:57 ` Jørgen Hansen
2024-04-10 6:29 ` Ira Weiny
2024-04-04 16:04 ` Jonathan Cameron
2024-04-04 16:13 ` Jonathan Cameron
2024-04-10 17:44 ` Alison Schofield
2024-05-06 18:34 ` Dan Williams
2024-03-24 23:18 ` [PATCH 15/26] range: Add range_overlaps() Ira Weiny
2024-03-25 18:33 ` David Sterba
2024-03-25 21:24 ` Davidlohr Bueso
2024-03-26 12:51 ` Johannes Thumshirn
2024-03-27 17:36 ` fan
2024-03-28 20:09 ` Dave Jiang
2024-04-04 16:06 ` Jonathan Cameron
2024-03-24 23:18 ` [PATCH 16/26] cxl/extent: Realize extent devices ira.weiny
2024-03-27 22:34 ` fan
2024-03-28 21:11 ` Dave Jiang
2024-04-24 19:57 ` Ira Weiny
2024-04-04 16:32 ` Jonathan Cameron
2024-04-30 3:23 ` Ira Weiny
2024-05-02 21:12 ` Dan Williams
2024-05-06 4:35 ` Ira Weiny
2024-04-11 0:09 ` Alison Schofield
2024-05-07 1:30 ` Dan Williams
2024-03-24 23:18 ` [PATCH 17/26] dax/region: Create extent resources on DAX region driver load ira.weiny
2024-04-04 16:36 ` Jonathan Cameron
2024-04-09 16:22 ` fan
2024-05-07 2:31 ` Dan Williams
2024-03-24 23:18 ` [PATCH 18/26] cxl/mem: Handle DCD add & release capacity events ira.weiny
2024-04-04 17:03 ` Jonathan Cameron
2024-05-07 5:04 ` Dan Williams
2024-03-24 23:18 ` [PATCH 19/26] dax/bus: Factor out dev dax resize logic Ira Weiny
2024-04-04 17:15 ` Jonathan Cameron
2024-03-24 23:18 ` [PATCH 20/26] dax: Document dax dev range tuple Ira Weiny
2024-04-01 17:06 ` Dave Jiang
2024-04-04 17:19 ` Jonathan Cameron
2024-03-24 23:18 ` [PATCH 21/26] dax/region: Prevent range mapping allocation on sparse regions Ira Weiny
2024-04-01 17:07 ` Dave Jiang
2024-04-10 23:02 ` Alison Schofield
2024-03-24 23:18 ` [PATCH 22/26] dax/region: Support DAX device creation on sparse DAX regions Ira Weiny
2024-04-04 17:36 ` Jonathan Cameron
2024-03-24 23:18 ` [PATCH 23/26] cxl/mem: Trace Dynamic capacity Event Record ira.weiny
2024-04-01 17:56 ` Dave Jiang
2024-04-04 17:38 ` Jonathan Cameron
2024-04-10 17:03 ` Alison Schofield
2024-03-24 23:18 ` [PATCH 24/26] tools/testing/cxl: Make event logs dynamic Ira Weiny
2024-03-24 23:18 ` [PATCH 25/26] tools/testing/cxl: Add DC Regions to mock mem data Ira Weiny
2024-03-24 23:18 ` [PATCH 26/26] tools/testing/cxl: Add Dynamic Capacity events Ira Weiny
2024-03-25 19:24 ` [PATCH 00/26] DCD: Add support for Dynamic Capacity Devices (DCD) fan
2024-03-28 5:20 ` Ira Weiny
2024-04-03 20:39 ` Jonathan Cameron
2024-04-04 10:20 ` Jonathan Cameron
2024-04-04 17:49 ` Jonathan Cameron
2024-05-01 23:49 ` Ira Weiny
2024-05-03 9:20 ` Jonathan Cameron
2024-05-06 4:24 ` Ira Weiny
2024-05-08 14:43 ` Jonathan Cameron
2024-04-10 18:01 ` Alison Schofield
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