Messages in this thread | | | Date | Wed, 29 Jun 2011 23:09:26 -0700 | Subject | Re: Ioctl in 2.6.35.22 change the argument value? | From | 孙子荀 <> |
| |
Hello everybody,
When I want to get the block size about the block device(DM or real),I use the system API like "ioctl(int fd, BLKGETSIZE,long size)". Everything works fine. But when I pass the third parameter whose type is "int", the first parameter fd will be changed to zero. It only happened on x86_64 and 2.6.35 ,on 2.6.38 and 32bit will not occur, I've already tested on them. (My PC:Linux server-group 2.6.35-22-server #33-Ubuntu SMP Sun Sep 19 20:48:58 UTC 2010 x86_64 GNU/Linux) here is the test code: int main(){ int fd; int blksize ; fd = open("/dev/sda",O_RDONLY,0); ioctl(fd, BLKGETSIZE,&blksize) ; close(fd); } If I change the fd type as long( int fd ==> long fd ) , won't occur again. I quite sure the ioctl syscall when return to userspace changes the fd's value. (gdb) r Starting program: /home/test/main 10 fd = open("/dev/sda",O_RDONLY,0); (gdb) 0x00000000004005a7 <+35>: callq 0x400490 <open@plt> 0x00000000004005ac <+40>: mov %eax,-0x4(%rbp) 0x00000000004005af <+43>: lea -0x8(%rbp),%rdx 0x00000000004005b3 <+47>: mov -0x4(%rbp),%eax 0x00000000004005b6 <+50>: mov $0x1260,%esi => 0x00000000004005bb <+55>: mov %eax,%edi 0x00000000004005bd <+57>: mov $0x0,%eax 0x00000000004005c2 <+62>: callq 0x400470 <ioctl@plt> 0x00000000004005c7 <+67>: mov -0x4(%rbp),%eax (gdb) ni 0x00000000004005bd 11 ioctl(fd, BLKGETSIZE,&blksize) ; (gdb) p $edi $1 = 5 (gdb) n 12 close(fd); (gdb) p $edi $3 = 5 (gdb) p fd $4 = 0 And I also find that in the function : "int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,unsigned long arg)" If it's case<BLKBSZGET BLKPBSZGET> which return put_uint() will be fine ,I mean the fd, and that was opposite to the case<BLKGETSIZE BLKGETSIZE64> which return put_long() ; Dose anybody now which patch after 2.6.35 slove the problem ?I just guess about restore_all(arch/x86/include/). thanks a lot! I will be gratefull for u help. Thanks a lot. Thanks a million! -- Regards, Sri. -- 2011-06-30
--------------------------------------------------------------------------------
faye.zixun
| |