linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Omar Sandoval <osandov@osandov.com>
To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
	Eric Biederman <ebiederm@xmission.com>,
	James Morse <james.morse@arm.com>,
	Bhupesh Sharma <bhsharma@redhat.com>,
	kernel-team@fb.com
Subject: [PATCH v4 3/9] proc/kcore: replace kclist_lock rwlock with rwsem
Date: Wed, 25 Jul 2018 16:59:14 -0700	[thread overview]
Message-ID: <51ba5cba7c43ec5ddce8023054c99943fad02b6d.1532563124.git.osandov@fb.com> (raw)
In-Reply-To: <cover.1532563124.git.osandov@fb.com>

From: Omar Sandoval <osandov@fb.com>

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.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 fs/proc/kcore.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index e83f15a4f66d..ae43a97d511d 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -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))
-- 
2.18.0

  parent reply	other threads:[~2018-07-26  1:13 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-25 23:59 [PATCH v4 0/9] /proc/kcore improvements Omar Sandoval
2018-07-25 23:59 ` [PATCH v4 1/9] proc/kcore: don't grab lock for kclist_add() Omar Sandoval
2018-08-07  5:05   ` Bhupesh Sharma
2018-07-25 23:59 ` [PATCH v4 2/9] proc/kcore: don't grab lock for memory hotplug notifier Omar Sandoval
2018-07-25 23:59 ` Omar Sandoval [this message]
2018-07-25 23:59 ` [PATCH v4 4/9] proc/kcore: fix memory hotplug vs multiple opens race Omar Sandoval
2018-07-25 23:59 ` [PATCH v4 5/9] proc/kcore: hold lock during read Omar Sandoval
2018-07-25 23:59 ` [PATCH v4 6/9] proc/kcore: clean up ELF header generation Omar Sandoval
2018-07-25 23:59 ` [PATCH v4 7/9] proc/kcore: optimize multiple page reads Omar Sandoval
2018-07-25 23:59 ` [PATCH v4 8/9] crash_core: use VMCOREINFO_SYMBOL_ARRAY() for swapper_pg_dir Omar Sandoval
2018-07-25 23:59 ` [PATCH v4 9/9] proc/kcore: add vmcoreinfo note to /proc/kcore Omar Sandoval

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=51ba5cba7c43ec5ddce8023054c99943fad02b6d.1532563124.git.osandov@fb.com \
    --to=osandov@osandov.com \
    --cc=adobriyan@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=bhsharma@redhat.com \
    --cc=ebiederm@xmission.com \
    --cc=james.morse@arm.com \
    --cc=kernel-team@fb.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).