Fix select on /proc files without ->poll (dd23aae4) · Commits · 戴 / test

Taneli Vähäkangas <vahakang@cs.helsinki.fi> reported that commit aka "Fix rmmod/read/write races in /proc entries" broke SBCL + SLIME combo. The old code in do_select() used DEFAULT_POLLMASK, if couldn't find ->poll handler. The new code makes ->poll always there and returns 0 by default, which is not correct. Return DEFAULT_POLLMASK instead. Steps to reproduce: install emacs, SBCL, SLIME emacs M-x slime in *inferior-lisp* buffer [watch it doing "Connecting to Swank on port X.."] Please, apply before 2.6.23. P.S.: why SBCL can't just read(2) /proc/cpuinfo is a mystery. Signed-off-by:

Alexey Dobriyan <adobriyan@gmail.com> Cc: T Taneli Vahakangas <vahakang@cs.helsinki.fi> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/inode.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -11,6 +11,7 @@
		#include <linux/string.h>
		#include <linux/stat.h>
		#include <linux/completion.h>
		#include <linux/poll.h>
		#include <linux/file.h>
		#include <linux/limits.h>
		#include <linux/init.h>
		@@ -232,7 +233,7 @@ static ssize_t proc_reg_write(struct file file, const char __user buf, size_t
		static unsigned int proc_reg_poll(struct file file, struct poll_table_struct pts)
		{
		struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
		unsigned int rv = 0;
		unsigned int rv = DEFAULT_POLLMASK;
		unsigned int (poll)(struct file , struct poll_table_struct *);

		spin_lock(&pde->pde_unload_lock);

fs/select.c

+0 −2

Original line number	Diff line number	Diff line
		@@ -26,8 +26,6 @@

		#include <asm/uaccess.h>

		#define DEFAULT_POLLMASK (POLLIN \| POLLOUT \| POLLRDNORM \| POLLWRNORM)

		struct poll_table_page {
		struct poll_table_page * next;
		struct poll_table_entry * entry;

include/linux/poll.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -21,6 +21,8 @@
		#define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
		#define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))

		#define DEFAULT_POLLMASK (POLLIN \| POLLOUT \| POLLRDNORM \| POLLWRNORM)

		struct poll_table_struct;

		/*

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