path: root/fs/signalfd.c
diff options
authorEric W. Biederman <ebiederm@xmission.com>2018-09-25 11:27:20 +0200
committerEric W. Biederman <ebiederm@xmission.com>2018-10-03 16:47:43 +0200
commitae7795bc6187a15ec51cf258abae656a625f9980 (patch)
tree2456aa85c6b4be1ac58e272393056c0edbee038a /fs/signalfd.c
parent4cd2e0e70af6897ca2247fa1ffb1553ca16b4903 (diff)
signal: Distinguish between kernel_siginfo and siginfo
Linus recently observed that if we did not worry about the padding member in struct siginfo it is only about 48 bytes, and 48 bytes is much nicer than 128 bytes for allocating on the stack and copying around in the kernel. The obvious thing of only adding the padding when userspace is including siginfo.h won't work as there are sigframe definitions in the kernel that embed struct siginfo. So split siginfo in two; kernel_siginfo and siginfo. Keeping the traditional name for the userspace definition. While the version that is used internally to the kernel and ultimately will not be padded to 128 bytes is called kernel_siginfo. The definition of struct kernel_siginfo I have put in include/signal_types.h A set of buildtime checks has been added to verify the two structures have the same field offsets. To make it easy to verify the change kernel_siginfo retains the same size as siginfo. The reduction in size comes in a following change. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'fs/signalfd.c')
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/signalfd.c b/fs/signalfd.c
index 4fcd1498acf5..757afc7c5895 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -79,7 +79,7 @@ static __poll_t signalfd_poll(struct file *file, poll_table *wait)
* Copied from copy_siginfo_to_user() in kernel/signal.c
static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
- siginfo_t const *kinfo)
+ kernel_siginfo_t const *kinfo)
struct signalfd_siginfo new;
@@ -163,7 +163,7 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
return sizeof(*uinfo);
-static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
+static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, kernel_siginfo_t *info,
int nonblock)
ssize_t ret;
@@ -215,7 +215,7 @@ static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
struct signalfd_siginfo __user *siginfo;
int nonblock = file->f_flags & O_NONBLOCK;
ssize_t ret, total = 0;
- siginfo_t info;
+ kernel_siginfo_t info;
count /= sizeof(struct signalfd_siginfo);
if (!count)