The patch titled
Subject: signalfd: add ability to return siginfo in a raw format
has been added to the -mm tree. Its filename is
signalfd-add-ability-to-return-siginfo-in-a-raw-format-v2.patch
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------------------------------------------------------
From: Andrey Vagin <avagin@xxxxxxxxxx>
Subject: signalfd: add ability to return siginfo in a raw format
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.
Signed-off-by: Andrey Vagin <avagin@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/signalfd.c | 64 +++++++++++++++++++++++++++++---
include/uapi/linux/signalfd.h | 1
2 files changed, 60 insertions(+), 5 deletions(-)
diff -puN fs/signalfd.c~signalfd-add-ability-to-return-siginfo-in-a-raw-format-v2 fs/signalfd.c
--- a/fs/signalfd.c~signalfd-add-ability-to-return-siginfo-in-a-raw-format-v2
+++ a/fs/signalfd.c
@@ -30,6 +30,7 @@
#include <linux/signalfd.h>
#include <linux/syscalls.h>
#include <linux/proc_fs.h>
+#include <linux/compat.h>
void signalfd_cleanup(struct sighand_struct *sighand)
{
@@ -74,6 +75,38 @@ static unsigned int signalfd_poll(struct
}
/*
+ * Copy a whole siginfo into users spaces.
+ * The main idea of this format is that it should be enough
+ * for restoring siginfo back into the kernel.
+ */
+static int signalfd_copy_raw_info(struct signalfd_siginfo __user *siginfo,
+ siginfo_t *kinfo)
+{
+ siginfo_t *uinfo = (siginfo_t *) siginfo;
+ int err;
+
+ BUILD_BUG_ON(sizeof(siginfo_t) != sizeof(struct signalfd_siginfo));
+
+ err = __clear_user(uinfo, sizeof(*uinfo));
+
+#ifdef CONFIG_COMPAT
+ if (unlikely(is_compat_task())) {
+ compat_siginfo_t *compat_uinfo = (compat_siginfo_t *) siginfo;
+
+ err |= copy_siginfo_to_user32(compat_uinfo, kinfo);
+ err |= put_user(kinfo->si_code, &compat_uinfo->si_code);
+
+ return err ? -EFAULT: sizeof(*compat_uinfo);
+ }
+#endif
+
+ err |= copy_siginfo_to_user(uinfo, kinfo);
+ err |= put_user(kinfo->si_code, &uinfo->si_code);
+
+ return err ? -EFAULT: sizeof(*uinfo);
+}
+
+/*
* Copied from copy_siginfo_to_user() in kernel/signal.c
*/
static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
@@ -205,6 +238,7 @@ static ssize_t signalfd_read(struct file
struct signalfd_ctx *ctx = file->private_data;
struct signalfd_siginfo __user *siginfo;
int nonblock = file->f_flags & O_NONBLOCK;
+ bool raw = file->f_flags & SFD_RAW;
ssize_t ret, total = 0;
siginfo_t info;
@@ -217,7 +251,12 @@ static ssize_t signalfd_read(struct file
ret = signalfd_dequeue(ctx, &info, nonblock);
if (unlikely(ret <= 0))
break;
- ret = signalfd_copyinfo(siginfo, &info);
+
+ if (raw)
+ ret = signalfd_copy_raw_info(siginfo, &info);
+ else
+ ret = signalfd_copyinfo(siginfo, &info);
+
if (ret < 0)
break;
siginfo++;
@@ -262,7 +301,7 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sig
BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
- if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
+ if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK | SFD_RAW))
return -EINVAL;
if (sizemask != sizeof(sigset_t) ||
@@ -272,20 +311,35 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sig
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);
} else {
struct fd f = fdget(ufd);
if (!f.file)
@@ -302,7 +356,7 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sig
wake_up(¤t->sighand->signalfd_wqh);
fdput(f);
}
-
+out:
return ufd;
}
diff -puN include/uapi/linux/signalfd.h~signalfd-add-ability-to-return-siginfo-in-a-raw-format-v2 include/uapi/linux/signalfd.h
--- a/include/uapi/linux/signalfd.h~signalfd-add-ability-to-return-siginfo-in-a-raw-format-v2
+++ a/include/uapi/linux/signalfd.h
@@ -15,6 +15,7 @@
/* Flags for signalfd4. */
#define SFD_CLOEXEC O_CLOEXEC
#define SFD_NONBLOCK O_NONBLOCK
+#define SFD_RAW O_DIRECT
struct signalfd_siginfo {
__u32 ssi_signo;
_
Patches currently in -mm which might be from avagin@xxxxxxxxxx are
signal-allow-to-send-any-siginfo-to-itself.patch
signalfd-add-ability-to-return-siginfo-in-a-raw-format-v2.patch
signalfd-add-ability-to-return-siginfo-in-a-raw-format-v2-fix.patch
signalfd-add-ability-to-read-siginfo-s-without-dequeuing-signals-v4.patch
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