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Mon, 29 Apr 2024 06:38:15 -0700 (PDT) Message-ID: <31f2dd75-4217-4110-8577-78fb77082299@suse.com> Date: Mon, 29 Apr 2024 15:38:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 06/17] xen/riscv: introduce cmpxchg.h Content-Language: en-US To: Oleksii Kurochko Cc: Alistair Francis , Bob Eshleman , Connor Davis , Andrew Cooper , George Dunlap , Julien Grall , Stefano Stabellini , xen-devel@lists.xenproject.org References: <6e068a2531f3ecbb7858739ecb5249d22ee01fff.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: <6e068a2531f3ecbb7858739ecb5249d22ee01fff.1713347222.git.oleksii.kurochko@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 17.04.2024 12:04, Oleksii Kurochko wrote: > +/* > + * This function doesn't exist, so you'll get a linker error > + * if something tries to do an invalid xchg(). > + */ > +extern void __bad_xchg(volatile void *ptr, int size); > + > +static always_inline unsigned long __xchg(volatile void *ptr, unsigned long new, int size) > +{ > + unsigned long ret; > + > + switch ( size ) > + { > + case 1: > + ret = emulate_xchg_1_2((volatile uint8_t *)ptr, new, ".aq", ".aqrl"); > + break; > + case 2: > + ret = emulate_xchg_1_2((volatile uint16_t *)ptr, new, ".aq", ".aqrl"); > + break; > + case 4: > + _amoswap_generic((volatile uint32_t *)ptr, new, ret, ".w.aqrl"); > + break; > +#ifndef CONFIG_RISCV_32 > + case 8: > + _amoswap_generic((volatile uint64_t *)ptr, new, ret, ".d.aqrl"); > + break; > +#endif > + default: > + __bad_xchg(ptr, size), ret = 0; > + } I see no real reason to use a comma expression here, the more that "break" needs adding anyway. I wonder why here you don't use ... > +/* This function doesn't exist, so you'll get a linker error > + if something tries to do an invalid cmpxchg(). */ > +extern unsigned long __bad_cmpxchg(volatile void *ptr, int size); > + > +/* > + * Atomic compare and exchange. Compare OLD with MEM, if identical, > + * store NEW in MEM. Return the initial value in MEM. Success is > + * indicated by comparing RETURN with OLD. > + */ > +static always_inline unsigned long __cmpxchg(volatile void *ptr, > + unsigned long old, > + unsigned long new, > + int size) > +{ > + unsigned long ret; > + > + switch ( size ) > + { > + case 1: > + ret = emulate_cmpxchg_1_2((volatile uint8_t *)ptr, old, new, > + ".aq", ".aqrl"); > + break; > + case 2: > + ret = emulate_cmpxchg_1_2((volatile uint16_t *)ptr, old, new, > + ".aq", ".aqrl"); > + break; > + case 4: > + ret = _generic_cmpxchg((volatile uint32_t *)ptr, old, new, > + ".w.aq", ".w.aqrl"); > + break; > +#ifndef CONFIG_32BIT > + case 8: > + ret = _generic_cmpxchg((volatile uint64_t *)ptr, old, new, > + ".d.aq", ".d.aqrl"); > + break; > +#endif > + default: > + return __bad_cmpxchg(ptr, size); ... the approach used here. Also (style nit) the comment on __bad_cmpxchg() is malformed, unlike that ahead of __bad_xchg(). Jan