From: Ira Weiny <ira.weiny@intel.com>
To: Dan Williams <dan.j.williams@intel.com>,
Ira Weiny <ira.weiny@intel.com>,
Alison Schofield <alison.schofield@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: Sun, 5 May 2024 20:46:59 -0700 [thread overview]
Message-ID: <663852b3806f1_258421294be@iweiny-mobl.notmuch> (raw)
In-Reply-To: <6635b5e0e3954_1aefb294bf@dwillia2-mobl3.amr.corp.intel.com.notmuch>
Dan Williams wrote:
> Ira Weiny wrote:
> > 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.
>
> Where did the "quite a bit more code" come from? A change that moves
> unnecessary code under a lock and is larger than just incrementally
> extending the status quo does not feel like a cleanup.
I'll drop the patch.
Ira
>
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index 7d97790b893d..0dc886bc22c6 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -411,11 +411,12 @@ 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;
> + int rc, dcd;
>
> switch (mode) {
> case CXL_DECODER_RAM:
> case CXL_DECODER_PMEM:
> + case CXL_DECODER_DC0 ... CXL_DECODER_DC7:
> break;
> default:
> dev_dbg(dev, "unsupported mode: %d\n", mode);
> @@ -442,6 +443,11 @@ int cxl_dpa_set_mode(struct cxl_endpoint_decoder *cxled,
> rc = -ENXIO;
> goto out;
> }
> + dcd = dc_mode_to_region_index(mode);
> + if (resource_size(&cxlds->dc_res[dcd]) == 0) {
> + dev_dbg(dev, "no available dynamic capacity\n");
> + goto out;
> + }
>
> cxled->mode = mode;
> rc = 0;
next prev parent reply other threads:[~2024-05-06 3:47 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
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 [this message]
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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