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Re: [PATCH v3] misra: add deviations of MISRA C Rule 5.5


  • To: Jan Beulich <jbeulich@xxxxxxxx>
  • From: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
  • Date: Thu, 31 Jul 2025 09:39:34 +0200
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  • Cc: Dmytro Prokopchuk1 <dmytro_prokopchuk1@xxxxxxxx>, Doug Goldstein <cardoe@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Julien Grall <julien@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • Delivery-date: Thu, 31 Jul 2025 07:39:48 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 2025-07-31 09:15, Jan Beulich wrote:
On 30.07.2025 23:39, Dmytro Prokopchuk1 wrote:
MISRA C Rule 5.5 states that: "Identifiers shall
be distinct from macro names".

Update ECLAIR configuration to deviate clashes:
specify the macros that should be ignored.
Update deviations.rst and rules.rst accordingly.

Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>

Nit (along the lines of my comments on the other patch): Make better use of line
capacity here.

--- a/automation/eclair_analysis/ECLAIR/deviations.ecl
+++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
@@ -117,6 +117,16 @@ it defines would (in the common case) be already defined. Peer reviewed by the c -config=MC3A2.R5.5,reports+={deliberate, "any_area(decl(kind(function))||any_loc(macro(name(memcpy||memset||memmove))))&&any_area(any_loc(file(^xen/common/libelf/libelf-private\\.h$)))"}
 -doc_end

+-doc_begin="Clashes between bitops function and macro names are deliberate.
+These macros are needed for input validation and error handling."
+-config=MC3A2.R5.5,ignored_macros+="name(__test_and_set_bit||__test_and_clear_bit||__test_and_change_bit||test_bit||set_bit||clear_bit||change_bit||test_and_set_bit||test_and_clear_bit||test_and_change_bit)"
+-doc_end

I have no idea whether regular expressions could be used here. If so, shortening
this at least some may be desirable.


It's possible, without using name(_): e.g., ignored_macros+="^(__)?test_and_(set|clear|change)?_bit$

+-doc_begin="Clashes between grant table functions and macros names are deliberate. +These macros address differences in argument count during compile-time, effectively discarding unused parameters to avoid warnings or errors related to them."
+-config=MC3A2.R5.5,ignored_macros+="name(update_gnttab_par||parse_gnttab_limit)"
+-doc_end

No restriction to common/grant_table.c?

--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -142,6 +142,28 @@ Deviations related to MISRA C:2012 Rules:
        memmove.
      - Tagged as `deliberate` for ECLAIR.

+   * - R5.5
+ - Clashes between bitops ('__test_and_set_bit', '__test_and_clear_bit', + '__test_and_change_bit', 'test_bit', 'set_bit', 'clear_bit', 'change_bit', + 'test_and_set_bit', 'test_and_clear_bit', 'test_and_change_bit') + functions and macros names are deliberate and are needed for input

Nit: "macro names"

+ validation and error handling, ensures that the size of the object being

s/ensures/to ensure/ ?

+ pointed to by 'addr' meets the minimum requirements for the bit operation,

'addr' is pretty meaningless here.

+ preventing unsafe operations on improperly sized data types that could
+       lead to undefined behavior or memory corruption.
+ The macros encapsulate this conditional logic into a single, reusable form;
+       which simplifies the code, avoids redundant function call.

What's "redundant" referring to here?

+ Also this bitops API was inherited from Linux and should be kept for familiarity.

At least this line is clearly beyond 80 chars.

Jan

--
Nicola Vetrini, B.Sc.
Software Engineer
BUGSENG (https://bugseng.com)
LinkedIn: https://www.linkedin.com/in/nicola-vetrini-a42471253



 


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