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From: "Verma, Vishal L" <vishal.l.verma@intel.com>
To: "Williams, Dan J" <dan.j.williams@intel.com>
Cc: "Widawsky, Ben" <ben.widawsky@intel.com>,
	"linux-cxl@vger.kernel.org" <linux-cxl@vger.kernel.org>,
	"nvdimm@lists.linux.dev" <nvdimm@lists.linux.dev>
Subject: Re: [ndctl PATCH v4 12/17] libcxl: add interfaces for label operations
Date: Thu, 14 Oct 2021 22:24:58 +0000	[thread overview]
Message-ID: <6637d78d46c03296b7c31452becbeed6236a8c83.camel@intel.com> (raw)
In-Reply-To: <CAPcyv4h49Cei27qLAL8oUmcpa=Su_VArrAEzGwt3VSbpCoxYTw@mail.gmail.com>

On Thu, 2021-10-14 at 14:27 -0700, Dan Williams wrote:
> On Thu, Oct 7, 2021 at 1:22 AM Vishal Verma <vishal.l.verma@intel.com> wrote:
> 

[..]

> > +
> > +CXL_EXPORT struct cxl_cmd *cxl_cmd_new_write_label(struct cxl_memdev *memdev,
> > +               void *lsa_buf, unsigned int offset, unsigned int length)
> > +{
> > +       struct cxl_ctx *ctx = cxl_memdev_get_ctx(memdev);
> > +       struct cxl_cmd_set_lsa *set_lsa;
> > +       struct cxl_cmd *cmd;
> > +       int rc;
> > +
> > +       cmd = cxl_cmd_new_generic(memdev, CXL_MEM_COMMAND_ID_SET_LSA);
> > +       if (!cmd)
> > +               return NULL;
> > +
> > +       /* this will allocate 'in.payload' */
> > +       rc = cxl_cmd_set_input_payload(cmd, NULL, sizeof(*set_lsa) + length);
> > +       if (rc) {
> > +               err(ctx, "%s: cmd setup failed: %s\n",
> > +                       cxl_memdev_get_devname(memdev), strerror(-rc));
> > +               goto out_fail;
> > +       }
> > +       set_lsa = (void *)cmd->send_cmd->in.payload;
> 
> ...the cast is still nagging at me especially when this knows what the
> payload is supposed to be. What about a helper per command type of the
> form:
> 
> struct cxl_cmd_$name *to_cxl_cmd_$name(struct cxl_cmd *cmd)
> {
>     if (cmd->send_cmd->id != CXL_MEM_COMMAND_ID_$NAME)
>         return NULL;
>     return (struct cxl_cmd_$name *) cmd->send_cmd->in.payload;
> }
> 
Is the nag just from using a void cast, or having to cast at all? I
think the void cast was just laziness - it should be cast to 
(struct cxl_cmd_$name *) instead of (void *).

Having a helper for to_cxl_cmd_$name() does look cleaner, but do we
need the validation step there? In all these cases, the cmd would've
been allocated just a few lines above, with cxl_cmd_new_generic(memdev,
CXL_MEM_COMMAND_ID_$NAME) - so it seems unnecessary?
> 

  parent reply	other threads:[~2021-10-14 22:25 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-07  8:21 [ndctl PATCH v4 00/17] Initial CXL support Vishal Verma
2021-10-07  8:21 ` [ndctl PATCH v4 01/17] ndctl: add .clang-format Vishal Verma
2021-10-07  8:21 ` [ndctl PATCH v4 02/17] cxl: add a cxl utility and libcxl library Vishal Verma
2021-10-07  8:21 ` [ndctl PATCH v4 03/17] cxl: add a local copy of the cxl_mem UAPI header Vishal Verma
2021-10-07  8:21 ` [ndctl PATCH v4 04/17] util: add the struct_size() helper from the kernel Vishal Verma
2021-10-14  2:40   ` Dan Williams
2021-10-07  8:21 ` [ndctl PATCH v4 05/17] libcxl: add support for command query and submission Vishal Verma
2021-10-14  2:53   ` Dan Williams
2021-10-07  8:21 ` [ndctl PATCH v4 06/17] libcxl: add support for the 'Identify Device' command Vishal Verma
2021-10-07  8:21 ` [ndctl PATCH v4 07/17] libcxl: add GET_HEALTH_INFO mailbox command and accessors Vishal Verma
2021-10-14 16:01   ` Dan Williams
2021-11-02 20:22     ` Verma, Vishal L
2021-11-02 20:27       ` Dan Williams
2021-10-07  8:21 ` [ndctl PATCH v4 08/17] libcxl: add support for the 'GET_LSA' command Vishal Verma
2021-10-14 16:35   ` Dan Williams
2021-10-14 20:06     ` Verma, Vishal L
2021-10-14 20:55       ` Dan Williams
2021-10-07  8:21 ` [ndctl PATCH v4 09/17] util/hexdump: Add a util helper to print a buffer in hex Vishal Verma
2021-10-14 16:48   ` Dan Williams
2021-10-14 20:33     ` Verma, Vishal L
2021-10-14 22:39       ` Dan Williams
2021-11-02 20:25         ` Verma, Vishal L
2021-10-07  8:21 ` [ndctl PATCH v4 10/17] libcxl: add label_size to cxl_memdev, and an API to retrieve it Vishal Verma
2021-10-14 18:24   ` Dan Williams
2021-10-14 21:50     ` Verma, Vishal L
2021-10-07  8:21 ` [ndctl PATCH v4 11/17] libcxl: add a stub interface to determine whether a memdev is active Vishal Verma
2021-10-14 19:59   ` Dan Williams
2021-10-07  8:21 ` [ndctl PATCH v4 12/17] libcxl: add interfaces for label operations Vishal Verma
2021-10-14 21:27   ` Dan Williams
2021-10-14 22:18     ` Verma, Vishal L
2021-10-14 22:24     ` Verma, Vishal L [this message]
2021-10-14 22:45       ` Dan Williams
2021-10-07  8:21 ` [ndctl PATCH v4 13/17] cxl: add commands to read, write, and zero labels Vishal Verma
2021-10-14 22:34   ` Dan Williams
2021-10-07  8:21 ` [ndctl PATCH v4 14/17] Documentation/cxl: add library API documentation Vishal Verma
2021-10-14 23:31   ` Dan Williams
2021-11-05 18:58   ` Dan Williams
2021-10-07  8:21 ` [ndctl PATCH v4 15/17] ndctl: Add CXL packages to the RPM spec Vishal Verma
2021-10-14 23:33   ` Dan Williams
2021-10-07  8:21 ` [ndctl PATCH v4 16/17] cxl-cli: add bash completion Vishal Verma
2021-10-14 23:34   ` Dan Williams
2021-10-07  8:21 ` [ndctl PATCH v4 17/17] cxl: add health information to cxl-list Vishal Verma
2021-10-11 22:07   ` Verma, Vishal L
2021-10-15  0:09     ` Dan Williams
2021-10-14 23:42   ` Verma, Vishal L
2021-10-15 21:15     ` Dan Williams

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