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Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] > > On Tue, Aug 19, 2025 at 1:08 PM Qianfeng Rong wrote: >> 在 2025/8/19 17:46, Andy Shevchenko 写道: >>> On Tue, Aug 19, 2025 at 11:56 AM Qianfeng Rong wrote: > ... > >>> While this change is correct... >>>> sensor->freq_avail = >>>> - devm_kzalloc(&iio_dev->dev, >>>> - sizeof(*sensor->freq_avail) * >>>> - (sensor->sensor_info->intervals.count * 2), >>>> + devm_kcalloc(&iio_dev->dev, >>>> + sensor->sensor_info->intervals.count * 2, >>> ...I would also switch this to use array_size() instead of explicit >>> multiplication as it will check for boundaries that are not static in >>> this case. >> I don't understand what "will check for boundaries that are not static in >> this case" means. Could you explain it to me? > intervals.count may be anything and of any type. Compiler may or may > not proof that it holds the value less than size_t / 2 (which may be > == int / 2 on 32-bit platforms). That's why it's better to use > array_size(intervals.count, 2), Thanks for taking the time to explain! The devm_kmalloc_array() function implements a check function similar to array_size() by default. devm_kmalloc_array(): static inline void *devm_kmalloc_array(struct device *dev, size_t n, size_t size, gfp_t flags) {     size_t bytes;     if (unlikely(check_mul_overflow(n, size, &bytes)))         return NULL;     return devm_kmalloc(dev, bytes, flags); } static inline void *devm_kcalloc(struct device *dev, size_t n, size_t size, gfp_t flags) {     return devm_kmalloc_array(dev, n, size, flags | __GFP_ZERO); } array_size(): static inline size_t __must_check size_mul(size_t factor1, size_t factor2) {     size_t bytes;     if (check_mul_overflow(factor1, factor2, &bytes))         return SIZE_MAX;     return bytes; } #define array_size(a, b)    size_mul(a, b) > >> I've experimented with the following command and found that kmalloc_array() >> generates fewer instructions than kmalloc(array_size()): >> objdump -dSl --prefix-addresses .o > It's about the second parameter in devm_kcalloc(), and of course it > may generate less instructions but it's irrelevant to my comment. > > Best regards, Qianfeng