On 12/28, Andrey Vagin wrote:
signalfd should be called with the flag SFD_RAW for that.
signalfd_siginfo is not full for siginfo with a negative si_code.
copy_siginfo_to_user() is copied a full siginfo to user-space, if
si_code is negative. signalfd_copyinfo() doesn't do that and can't be
expanded, because it has not compatible format with siginfo_t.
Another problem is that a constant __SI_* is removed from si_code.
It's not a problem for usual applications, because they expect
a defined type of siginfo (internal logic).
When we want to dump pending signals, we can't predict a type of
siginfo, so we should get it from kernel.
The main idea of the raw format is that it should be enough for
restoring exactly the same siginfo for the current process.
This functionality is required for checkpointing pending signals.
And this should be used along with pread().
I won't argue, but perhaps we should simply postulate that pread()
always dumps siginfo in raw format and avoid the new flag?
quoted hunk
@@ -272,20 +311,35 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
signotset(&sigmask);
if (ufd == -1) {
+ struct file *file;
ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return -ENOMEM;
ctx->sigmask = sigmask;
+ ufd = get_unused_fd_flags(flags);
+ if (ufd < 0) {
+ kfree(ctx);
+ goto out;
+ }
+
/*
* When we call this, the initialization must be complete, since
* anon_inode_getfd() will install the fd.
*/
- ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
+ file = anon_inode_getfile("[signalfd]", &signalfd_fops, ctx,
O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
- if (ufd < 0)
+ if (IS_ERR(file)) {
+ put_unused_fd(ufd);
+ ufd = PTR_ERR(file);
kfree(ctx);
+ goto out;
+ }
+
+ file->f_flags |= flags & SFD_RAW;
+
+ fd_install(ufd, file);
And this is needed because we want to set more bits in f_flags/f_mode.
I am wondering if we can change anon_inode_getfd/getfile somehow so
that the user can pass more flags...
Or. Currently fops->open() is never used if this file_operations is used
by anon_inode_get*. So perhaps we can change anon_inode_getfile() to call
fops->open() if it is not zero before return?
OK, this is almost off-topic, please ignore.
Oleg.