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SubjectRe: [PATCH] fix wrong error code on interrupted close syscalls
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On Thursday, 10-Aug-2006 at 19:36 EDT, Ernie Petrides wrote:

> [...]
> The bottom line is that close() syscalls are not restartable, and
> thus -ERESTARTSYS return values should be mapped to -EINTR. This
> is consistent with the close(2) manual page. The fix is below.
> [...]
> --- linux-2.6.17/fs/open.c.orig
> +++ linux-2.6.17/fs/open.c
> @@ -1172,6 +1172,7 @@ asmlinkage long sys_close(unsigned int f
> struct file * filp;
> struct files_struct *files = current->files;
> struct fdtable *fdt;
> + int retval;
>
> spin_lock(&files->file_lock);
> fdt = files_fdtable(files);
> @@ -1184,7 +1185,10 @@ asmlinkage long sys_close(unsigned int f
> FD_CLR(fd, fdt->close_on_exec);
> __put_unused_fd(files, fd);
> spin_unlock(&files->file_lock);
> - return filp_close(filp, files);
> + retval = filp_close(filp, files);
> +
> + /* can't restart close syscall because file table entry was cleared */
> + return (retval == -ERESTARTSYS) ? -EINTR : retval;
>
> out_unlock:
> spin_unlock(&files->file_lock);


Hi, Andrew. Roland McGrath has pointed out to me that my original patch
for this problem only handles the case of ERESTARTSYS, but doesn't treat
the three other restart pseudo-error codes similarly.

I don't see how any code currently in the 2.6.17 source tree could possibly
result in any ERESTARTNOINTR, ERESTARTNOHAND, or ERESTART_RESTARTBLOCK
errors being sent back through filp_close().

But if you prefer the extra checks for completeness, feel free to add
the incremental patch below (on top of my previous patch to check for
ERESTARTSYS).

Cheers. -ernie



--- linux-2.6.17/fs/open.c.prev
+++ linux-2.6.17/fs/open.c
@@ -1188,7 +1188,13 @@ asmlinkage long sys_close(unsigned int f
retval = filp_close(filp, files);

/* can't restart close syscall because file table entry was cleared */
- return (retval == -ERESTARTSYS) ? -EINTR : retval;
+ if (unlikely(retval == -ERESTARTSYS ||
+ retval == -ERESTARTNOINTR ||
+ retval == -ERESTARTNOHAND ||
+ retval == -ERESTART_RESTARTBLOCK))
+ retval = -EINTR;
+
+ return retval;

out_unlock:
spin_unlock(&files->file_lock);
-
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