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Fri, 26 Apr 2024 03:51:33 -0700 (PDT) Message-ID: Date: Fri, 26 Apr 2024 12:51:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 03/17] xen/bitops: implement fls{l}() in common logic Content-Language: en-US To: Oleksii Cc: Stefano Stabellini , Julien Grall , Bertrand Marquis , Michal Orzel , Volodymyr Babchuk , Andrew Cooper , George Dunlap , Shawn Anastasio , =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , xen-devel@lists.xenproject.org References: <60bc710b990ed1d45741888df7e97cf25d150e61.1713347222.git.oleksii.kurochko@gmail.com> From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 26.04.2024 10:21, Oleksii wrote: > On Thu, 2024-04-25 at 17:44 +0200, Jan Beulich wrote: >> On 17.04.2024 12:04, Oleksii Kurochko wrote: >>> Return type was left 'int' because of the following compilation >>> error: >>> >>> ./include/xen/kernel.h:18:21: error: comparison of distinct pointer >>> types lacks a cast [-Werror] >>>        18 |         (void) (&_x == &_y);            \ >>>           |                     ^~ >>>     common/page_alloc.c:1843:34: note: in expansion of macro 'min' >>>      1843 |         unsigned int inc_order = min(MAX_ORDER, flsl(e >>> - s) - 1); >> >> Apart from this I'm okay with this patch, assuming Andrew's won't >> change in >> any conflicting way. As to the above - no, I don't see us having >> ffs() / ffsl() >> returning unsigned int, fls() / flsl() returning plain int. Even more >> so that, >> given the LHS variable's type, an unsigned quantity is really meant >> in the >> quoted code. > If I understand you correctly, it's acceptable for fls() / flsl() to > return 'int'. Therefore, I can update the commit message by removing > the part mentioning the compilation error, as it's expected for fls() / > flsl() to return 'int'. Is my understanding correct? No. I firmly object to ffs() and fls() being different in their return types. I'm sorry, I realize now that my earlier wording was ambiguous (at least missing "but" after the comma). Jan