On Fri, Jan 14, 2022 at 4:57 AM Vincent Whitchurch vincent.whitchurch@axis.com wrote:
On Fri, Jan 07, 2022 at 06:29:24AM +0100, Jim Cromie wrote:
#ifdef CONFIG_JUMP_LABEL
if (dp->flags & _DPRINTK_FLAGS_PRINT) {if (!(modifiers->flags & _DPRINTK_FLAGS_PRINT))
if (dp->flags & _DPRINTK_FLAGS_ENABLED) {if (!(modifiers->flags & _DPRINTK_FLAGS_ENABLED)) static_branch_disable(&dp->key.dd_key_true);
} else if (modifiers->flags & _DPRINTK_FLAGS_PRINT)
} else if (modifiers->flags & _DPRINTK_FLAGS_ENABLED) static_branch_enable(&dp->key.dd_key_true);#endif dp->flags = newflags; -- 2.33.1
I haven't tested it so I could be mistaken, but when _DPRINTK_FLAGS_ENABLED gets two flags in the next patch, it looks like this code still has the problem which I mentioned in https://lore.kernel.org/lkml/20211209150910.GA23668@axis.com/?
Yes, thanks for noticing. I missed that detail. Apriori, I dont know why bit-and of bit-or'd flags doesnt cover it, but I will take a careful look.
| I noticed a bug inside the CONFIG_JUMP_LABEL handling (also present | in the last version I posted) which should be fixed as part of the | diff below (I've added a comment). | [...] | #ifdef CONFIG_JUMP_LABEL | - if (dp->flags & _DPRINTK_FLAGS_PRINT) { | - if (!(modifiers->flags & _DPRINTK_FLAGS_PRINT)) | + if (dp->flags & _DPRINTK_FLAGS_ENABLE) { | + /* | + * The newflags check is to ensure that the | + * static branch doesn't get disabled in step | + * 3: | + * | + * (1) +pf | + * (2) +x | + * (3) -pf | + */ | + if (!(modifiers->flags & _DPRINTK_FLAGS_ENABLE) && | + !(newflags & _DPRINTK_FLAGS_ENABLE)) { | static_branch_disable(&dp->key.dd_key_true); | - } else if (modifiers->flags & _DPRINTK_FLAGS_PRINT) | + } | + } else if (modifiers->flags & _DPRINTK_FLAGS_ENABLE) { | static_branch_enable(&dp->key.dd_key_true); | + } | #endif