linux-kernel - Re: [PATCH v5 1/2] acpi: apei: remove the unused dead-code for SEA/NMI notification type

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Date:   Wed, 18 Oct 2017 11:04:28 +0800
From:   gengdongjiu <gengdongjiu@...wei.com>
To:     Borislav Petkov <bp@...e.de>
CC:     <tbaicar@...eaurora.org>, <james.morse@....com>,
        <will.deacon@....com>, <rjw@...ysocki.net>, <lenb@...nel.org>,
        <robert.moore@...el.com>, <lv.zheng@...el.com>,
        <mark.rutland@....com>, <kristina.martsenko@....com>,
        <mingo@...nel.org>, <punit.agrawal@....com>,
        <stephen.boyd@...aro.org>, <kamensky@...co.com>,
        <prarit@...hat.com>, <shiju.jose@...wei.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-acpi@...r.kernel.org>,
        <devel@...ica.org>, Wuquanming <wuquanming@...wei.com>,
        Huangshaoyu <huangshaoyu@...wei.com>
Subject: Re: [PATCH v5 1/2] acpi: apei: remove the unused dead-code for
 SEA/NMI notification type

Hi,Borislav

On 2017/10/18 0:43, Borislav Petkov wrote:
>> -}
>> -
> So GHES NMI notification method is x86-only AFAIK and HAVE_ACPI_APEI_NMI
> is selected only on x86. Why are you removing those guards? Does ARM
> have ACPI_HEST_NOTIFY_NMI notification type now too?

ARM does not have ACPI_HEST_NOTIFY_NMI notification, which should only used by x86.
In the code, I see those guards are never used. As you see, if the 'CONFIG_HAVE_ACPI_APEI_NMI'
does not defined in [1], it will print error info and goto [2], in the [2], it will return error,
then the probe for GHES NMI is failed. so those guards( ghes_nmi_add() and ghes_nmi_remove()) have no chance
to execute. so I redefine them to NULL for compiling[3].

    static int ghes_probe(struct platform_device *ghes_dev)
    {
      struct acpi_hest_generic *generic;
      struct ghes *ghes = NULL;

      int rc = -EINVAL;

       switch (generic->notify.type) {
	   ...................
       case ACPI_HEST_NOTIFY_NMI:                        [1]
          if (!IS_ENABLED(CONFIG_HAVE_ACPI_APEI_NMI)) {
              pr_warn(GHES_PFX "Generic hardware error source: %d notified via NMI interrupt is not supported!\n",
                  generic->header.source_id);
              goto err;
          }
           ..............
	  }
	  switch (generic->notify.type) {
          ...............
          case ACPI_HEST_NOTIFY_NMI:
             ghes_nmi_add(ghes);
             break;
          }
          ..........
 err:                                                [2]
      if (ghes) {
          ghes_fini(ghes);
          kfree(ghes);
      }
      return rc;
    }

[3]:
-static inline void ghes_nmi_add(struct ghes *ghes)
-{
-       pr_err(GHES_PFX "ID: %d, trying to add NMI notification which is not supported!\n",
-              ghes->generic->header.source_id);
-       BUG();
-}
-
-static inline void ghes_nmi_remove(struct ghes *ghes)
-{
-       pr_err(GHES_PFX "ID: %d, trying to remove NMI notification which is not supported!\n",
-              ghes->generic->header.source_id);
-       BUG();
-}
-
-static inline void ghes_nmi_init_cxt(void)
-{
-}
+static inline void ghes_nmi_add(struct ghes *ghes) { }
+static inline void ghes_nmi_remove(struct ghes *ghes) { }
+static inline void ghes_nmi_init_cxt(void) { }