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Commit 0b172f84 authored by Omar Sandoval's avatar Omar Sandoval Committed by Linus Torvalds
Browse files

proc/kcore: replace kclist_lock rwlock with rwsem 

Now we only need kclist_lock from user context and at fs init time, and
the following changes need to sleep while holding the kclist_lock.

Link: http://lkml.kernel.org/r/521ba449ebe921d905177410fee9222d07882f0d.1531953780.git.osandov@fb.com


Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bf531831

fs/proc/kcore.c

+10 −10
Original line number Diff line number Diff line
@@ -59,7 +59,7 @@ struct memelfnote 
};



static LIST_HEAD(kclist_head);

static DEFINE_RWLOCK(kclist_lock);

static DECLARE_RWSEM(kclist_lock);

static int kcore_need_update = 1;



/* This doesn't grab kclist_lock, so it should only be used at init time. */
@@ -117,7 +117,7 @@ static void __kcore_update_ram(struct list_head *list) 
	struct kcore_list *tmp, *pos;

	LIST_HEAD(garbage);



	write_lock(&kclist_lock);

	down_write(&kclist_lock);

	if (xchg(&kcore_need_update, 0)) {

		list_for_each_entry_safe(pos, tmp, &kclist_head, list) {

			if (pos->type == KCORE_RAM
@@ -128,7 +128,7 @@ static void __kcore_update_ram(struct list_head *list) 
	} else

		list_splice(list, &garbage);

	proc_root_kcore->size = get_kcore_size(&nphdr, &size);

	write_unlock(&kclist_lock);

	up_write(&kclist_lock);



	free_kclist_ents(&garbage);

}
@@ -451,11 +451,11 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) 
	int nphdr;

	unsigned long start;



	read_lock(&kclist_lock);

	down_read(&kclist_lock);

	size = get_kcore_size(&nphdr, &elf_buflen);



	if (buflen == 0 || *fpos >= size) {

		read_unlock(&kclist_lock);

		up_read(&kclist_lock);

		return 0;

	}
@@ -472,11 +472,11 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) 
			tsz = buflen;

		elf_buf = kzalloc(elf_buflen, GFP_ATOMIC);

		if (!elf_buf) {

			read_unlock(&kclist_lock);

			up_read(&kclist_lock);

			return -ENOMEM;

		}

		elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);

		read_unlock(&kclist_lock);

		up_read(&kclist_lock);

		if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {

			kfree(elf_buf);

			return -EFAULT;
@@ -491,7 +491,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) 
		if (buflen == 0)

			return acc;

	} else

		read_unlock(&kclist_lock);

		up_read(&kclist_lock);



	/*

	 * Check to see if our file offset matches with any of
@@ -504,12 +504,12 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) 
	while (buflen) {

		struct kcore_list *m;



		read_lock(&kclist_lock);

		down_read(&kclist_lock);

		list_for_each_entry(m, &kclist_head, list) {

			if (start >= m->addr && start < (m->addr+m->size))

				break;

		}

		read_unlock(&kclist_lock);

		up_read(&kclist_lock);



		if (&m->list == &kclist_head) {

			if (clear_user(buffer, tsz))