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SubjectRe: [2.6.28-rc1 regression] wmifinfo dockapp takes 100% of cpu (bisected)
On Sat, 25 Oct 2008 07:05:42 -0700
Arjan van de Ven <arjan@linux.intel.com> wrote:

> Carlos R. Mafra wrote:
>
>
> Hi,
>
> the line below is the key one:
>
> > select(4, [3], NULL, NULL, {0, 5000000}) = -1 EINVAL (Invalid
> > argument)
>
> the application gives us an invalid timeval; it should have been (5,
> 0) However, if the kernel accepted this before the kernel needs to
> now also accept it obviously, I'll look into it

This patch should fix it; I'm a bit worried that I need to fix up
userlands "mess", but ok. I also checked all other converted functions,
and only select has this problem. The problem is that the conversion
from microseconds to nanoseconds is overflowing ;-(

can you give this one a test?

diff --git a/fs/compat.c b/fs/compat.c
index fe3c9bf..95ceee6 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1680,9 +1680,16 @@ asmlinkage long compat_sys_select(int n, compat_ulong_t __user *inp,
int ret;

if (tvp) {
+ int i;
if (copy_from_user(&tv, tvp, sizeof(tv)))
return -EFAULT;

+ while (tv.tv_usec > USEC_PER_SEC && i < 1000) {
+ i++;
+ tv.tv_sec ++;
+ tv.tv_usec -= USEC_PER_SEC;
+ }
+
to = &end_time;
if (poll_select_set_timeout(to, tv.tv_sec,
tv.tv_usec * NSEC_PER_USEC))
diff --git a/fs/select.c b/fs/select.c
index 448e440..e4e7cdb 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -515,9 +515,16 @@ asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp,
int ret;

if (tvp) {
+ int i = 0;
if (copy_from_user(&tv, tvp, sizeof(tv)))
return -EFAULT;

+ while (tv.tv_usec > USEC_PER_SEC && i < 1000) {
+ i++;
+ tv.tv_sec ++;
+ tv.tv_usec -= USEC_PER_SEC;
+ }
+
to = &end_time;
if (poll_select_set_timeout(to, tv.tv_sec,
tv.tv_usec * NSEC_PER_USEC))
--
Arjan van de Ven Intel Open Source Technology Centre
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