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linux_ioctl_cdrom: reduce stack usage

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... by moving two ~2KB structures from stack to heap allocation.
I experienced stack overflow in linux emulation on i386 (8K stack)
when LINUX_DVD_READ_STRUCT ioctl was performed on atapicam cd
device and there was an error that resulted in additional quite
heavy stack use in cam layer.

Reviewed by:	dchagin
Approved by:	jhb (mentor)
This commit is contained in:
Andriy Gapon 2009-05-27 15:23:12 +00:00
parent ee1c1433e3
commit 93f0eafde3
1 changed files with 16 additions and 11 deletions
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27
sys/compat/linux/linux_ioctl.c
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@ -1556,23 +1556,28 @@ linux_ioctl_cdrom(struct thread *td, struct linux_ioctl_args *args)
/* LINUX_CDROMAUDIOBUFSIZ */
case LINUX_DVD_READ_STRUCT: {
l_dvd_struct lds;
struct dvd_struct bds;
l_dvd_struct *lds;
struct dvd_struct *bds;
error = copyin((void *)args->arg, &lds, sizeof(lds));
lds = malloc(sizeof(*lds), M_LINUX, M_WAITOK);
bds = malloc(sizeof(*bds), M_LINUX, M_WAITOK);
error = copyin((void *)args->arg, lds, sizeof(*lds));
if (error)
break;
error = linux_to_bsd_dvd_struct(&lds, &bds);
goto out;
error = linux_to_bsd_dvd_struct(lds, bds);
if (error)
break;
error = fo_ioctl(fp, DVDIOCREADSTRUCTURE, (caddr_t)&bds,
goto out;
error = fo_ioctl(fp, DVDIOCREADSTRUCTURE, (caddr_t)bds,
td->td_ucred, td);
if (error)
break;
error = bsd_to_linux_dvd_struct(&bds, &lds);
goto out;
error = bsd_to_linux_dvd_struct(bds, lds);
if (error)
break;
error = copyout(&lds, (void *)args->arg, sizeof(lds));
goto out;
error = copyout(lds, (void *)args->arg, sizeof(*lds));
out:
free(bds, M_LINUX);
free(lds, M_LINUX);
break;
}