d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

When writing out updated pollfd records when returning from

Browse Source 
poll(), only copy out the revents field, not the whole pollfd
structure.  Otherwise, if the events field is updated
concurrently by another thread, that update may be lost.

This issue apparently causes problems for the JDK on FreeBSD,
which expects the Linux behavior of not updating all fields
(somewhat oddly, Solaris does not implement the required
behavior, but presumably our adaptation of the JDK is based
on the Linux port?).

MFC after:      2 weeks
PR:		kern/130924
Submitted by:   Kurt Miller <kurt @ intricatesoftware.com>
Discussed with:	kib
This commit is contained in:
rwatson 2009-03-11 22:00:03 +00:00
parent 2548f05c6c
commit 843cb67ec0
1 changed files with 22 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
sys/kern/sys_generic.c
View File

@ -76,6 +76,7 @@ static MALLOC_DEFINE(M_IOCTLOPS, "ioctlops", "ioctl data buffer");
static MALLOC_DEFINE(M_SELECT, "select", "select() buffer");
MALLOC_DEFINE(M_IOV, "iov", "large iov's");
static int pollout(struct pollfd *, struct pollfd *, u_int);
static int pollscan(struct thread *, struct pollfd *, u_int);
static int pollrescan(struct thread *);
static int selscan(struct thread *, fd_mask **, fd_mask **, int);
@ -1128,7 +1129,7 @@ done:
if (error == EWOULDBLOCK)
error = 0;
if (error == 0) {
error = copyout(bits, uap->fds, ni);
error = pollout(bits, uap->fds, nfds);
if (error)
goto out;
}
@ -1182,6 +1183,26 @@ pollrescan(struct thread *td)
}
static int
pollout(fds, ufds, nfd)
struct pollfd *fds;
struct pollfd *ufds;
u_int nfd;
{
int error = 0;
u_int i = 0;
for (i = 0; i < nfd; i++) {
error = copyout(&fds->revents, &ufds->revents,
sizeof(ufds->revents));
if (error)
return (error);
fds++;
ufds++;
}
return (0);
}
static int
pollscan(td, fds, nfd)
struct thread *td;