Messages in this thread | | | Date | Wed, 8 Jun 2022 20:43:31 +0800 (CST) | From | "Chen Lin" <> | Subject | Re:Re: [PATCH v4] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag |
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At 2022-06-08 07:14:13, "Jakub Kicinski" <kuba@kernel.org> wrote: >On Tue, 7 Jun 2022 07:39:11 +0800 Chen Lin wrote: >> +static inline void *mtk_max_lro_buf_alloc(gfp_t gfp_mask) > >No need for inline, compiler will inline this anyway. > >> +{ >> + void *data; > >unsigned long data; then you can move the cast from the long line to >the return statement, saving us from the strange indentation. > >> + data = (void *)__get_free_pages(gfp_mask | >> + __GFP_COMP | __GFP_NOWARN, >> + get_order(mtk_max_frag_size(MTK_MAX_LRO_RX_LENGTH))); >> + >> + return data; >> +}
I'll do it like below : +static void *mtk_max_lro_buf_alloc(gfp_t gfp_mask) +{ + unsigned long data; + unsigned int size = mtk_max_frag_size(MTK_MAX_LRO_RX_LENGTH); + + data = __get_free_pages(gfp_mask | __GFP_COMP | __GFP_NOWARN, + get_order(size)); + + return (void *)data; +}
Through analysis of the ASM code from objdump, I confirmed that the inline is not necessary. Thanks for your tips.
Also, I confirmed that create a new local variable 'size' will not affect the generation of a constant 'order' parameter at compile time.
ASM code of calling 'mtk_max_lro_buf_alloc':
'mtk_max_lro_buf_alloc' inlined and 'order'(w1) is a constant 0x2 0000000000004530 <mtk_napi_rx>: ... 4a98: 52854400 mov w0, #0x2a20 // #10784 4a9c: 52800041 mov w1, #0x2 // #2 4aa0: 72a00080 movk w0, #0x4, lsl #16 4aa4: 94000000 bl 0 <__get_free_pages> 4aa8: f90033e0 str x0, [sp, #96]
0000000000000730 <mtk_rx_alloc>: ... 7fc: 2a1703e0 mov w0, w23 800: 52800041 mov w1, #0x2 // #2 804: 7140047f cmp w3, #0x1, lsl #12 808: 54fffe49 b.ls 7d0 <mtk_rx_alloc+0xa0> // b.plast 80c: 94000000 bl 0 <__get_free_pages>
The compiler is smart. | |