thefirst ECS <ecs...@yahoo.com> writes: > In order to help debug a certain discrepancy, I need to "simulate" an "echo 1 > > /proc/file" but doing it from kernel even when root file system is > unavailable. > > I have simulated it just fine via call_usermodehelper (with argv etc of "echo > 1 > /proc/file") from inside the kernel which triggers: > [ee897ec0] [c0122704] proc_reg_write+0x80/0xb4 > [ee897ef0] [c00d3b7c] vfs_write+0xb4/0x184 > > just as I had wanted. But now I need to trigger the "vfs_write" and > "proc_reg_write" but without using call_usermodehelper since I will be doing > it when root "/" is unavailable and so I can no longer access /bin/echo and > call the usermodehelper etc. So my question is how can I do that in kernel? > > Not sure if I'm supposed to look in fs read_write.c and fs.h and write a > method based on those or if there's some other way etc.
You don't say which proc file, which would be useful information. I'll assume it's /proc/sysrq-trigger based on your previous mail. Rather than trying to invoke the write path from inside the kernel, the simplest option is to just call __handle_sysrq() directly. cheers
