lustre-devel-lustre.org archive mirror
 help / color / mirror / Atom feed
From: James Simmons <jsimmons@infradead.org>
To: lustre-devel@lists.lustre.org
Subject: [lustre-devel] [PATCH 36/42] lustre: don't take spinlock to read a 'long'.
Date: Mon,  5 Oct 2020 20:06:15 -0400	[thread overview]
Message-ID: <1601942781-24950-37-git-send-email-jsimmons@infradead.org> (raw)
In-Reply-To: <1601942781-24950-1-git-send-email-jsimmons@infradead.org>

From: Mr NeilBrown <neilb@suse.de>

Reading a 'long' (or unsigned long) is always an atomic operation.
There is never a need to take a spinlock to just read a single 'long'.

There are several procfs/debugfs/sysfs handlers which needlessly take
a spinlock for this purpose.

This patch:
 - removes the taking of the spinlock
 - changes the printf to scnprintf() as appropriate
 - directly returns the value returned by scnprintf rather than
   storing it in a variable
 - accesses the 'long' as an arg to the scnprintf(), rather than
   introducing a variabe to hold it.

WC-bug-id: https://jira.whamcloud.com/browse/LU-6142
Lustre-commit: 023a9e4cde5498 ("LU-6142 lustre: don't take spinlock to read a 'long'.")
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Reviewed-on: https://review.whamcloud.com/39743
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.super@gmail.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: James Simmons <jsimmons@infradead.org>
---
 fs/lustre/llite/lproc_llite.c | 24 ++++++------------------
 fs/lustre/mdc/lproc_mdc.c     |  7 +------
 fs/lustre/osc/lproc_osc.c     | 23 ++++++++---------------
 3 files changed, 15 insertions(+), 39 deletions(-)

diff --git a/fs/lustre/llite/lproc_llite.c b/fs/lustre/llite/lproc_llite.c
index 54db7eb..9b1c392 100644
--- a/fs/lustre/llite/lproc_llite.c
+++ b/fs/lustre/llite/lproc_llite.c
@@ -326,13 +326,9 @@ static ssize_t max_read_ahead_mb_show(struct kobject *kobj,
 {
 	struct ll_sb_info *sbi = container_of(kobj, struct ll_sb_info,
 					      ll_kset.kobj);
-	unsigned long ra_max_mb;
 
-	spin_lock(&sbi->ll_lock);
-	ra_max_mb = PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages);
-	spin_unlock(&sbi->ll_lock);
-
-	return scnprintf(buf, PAGE_SIZE, "%lu\n", ra_max_mb);
+	return scnprintf(buf, PAGE_SIZE, "%lu\n",
+			 PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages));
 }
 
 static ssize_t max_read_ahead_mb_store(struct kobject *kobj,
@@ -374,13 +370,9 @@ static ssize_t max_read_ahead_per_file_mb_show(struct kobject *kobj,
 {
 	struct ll_sb_info *sbi = container_of(kobj, struct ll_sb_info,
 					      ll_kset.kobj);
-	unsigned long ra_max_file_mb;
 
-	spin_lock(&sbi->ll_lock);
-	ra_max_file_mb = PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages_per_file);
-	spin_unlock(&sbi->ll_lock);
-
-	return scnprintf(buf, PAGE_SIZE, "%lu\n", ra_max_file_mb);
+	return scnprintf(buf, PAGE_SIZE, "%lu\n",
+			 PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages_per_file));
 }
 
 static ssize_t max_read_ahead_per_file_mb_store(struct kobject *kobj,
@@ -419,13 +411,9 @@ static ssize_t max_read_ahead_whole_mb_show(struct kobject *kobj,
 {
 	struct ll_sb_info *sbi = container_of(kobj, struct ll_sb_info,
 					      ll_kset.kobj);
-	unsigned long ra_max_whole_mb;
-
-	spin_lock(&sbi->ll_lock);
-	ra_max_whole_mb = PAGES_TO_MiB(sbi->ll_ra_info.ra_max_read_ahead_whole_pages);
-	spin_unlock(&sbi->ll_lock);
 
-	return scnprintf(buf, PAGE_SIZE, "%lu\n", ra_max_whole_mb);
+	return scnprintf(buf, PAGE_SIZE, "%lu\n",
+			 PAGES_TO_MiB(sbi->ll_ra_info.ra_max_read_ahead_whole_pages));
 }
 
 static ssize_t max_read_ahead_whole_mb_store(struct kobject *kobj,
diff --git a/fs/lustre/mdc/lproc_mdc.c b/fs/lustre/mdc/lproc_mdc.c
index d7506ea..662be42 100644
--- a/fs/lustre/mdc/lproc_mdc.c
+++ b/fs/lustre/mdc/lproc_mdc.c
@@ -44,13 +44,8 @@ static int mdc_max_dirty_mb_seq_show(struct seq_file *m, void *v)
 {
 	struct obd_device *obd = m->private;
 	struct client_obd *cli = &obd->u.cli;
-	unsigned long val;
 
-	spin_lock(&cli->cl_loi_list_lock);
-	val = PAGES_TO_MiB(cli->cl_dirty_max_pages);
-	spin_unlock(&cli->cl_loi_list_lock);
-
-	seq_printf(m, "%lu\n", val);
+	seq_printf(m, "%lu\n", PAGES_TO_MiB(cli->cl_dirty_max_pages));
 	return 0;
 }
 
diff --git a/fs/lustre/osc/lproc_osc.c b/fs/lustre/osc/lproc_osc.c
index 14cbe54..7ea9530 100644
--- a/fs/lustre/osc/lproc_osc.c
+++ b/fs/lustre/osc/lproc_osc.c
@@ -87,7 +87,7 @@ static ssize_t max_rpcs_in_flight_show(struct kobject *kobj,
 					      obd_kset.kobj);
 	struct client_obd *cli = &obd->u.cli;
 
-	return sprintf(buf, "%u\n", cli->cl_max_rpcs_in_flight);
+	return scnprintf(buf, PAGE_SIZE, "%u\n", cli->cl_max_rpcs_in_flight);
 }
 
 static ssize_t max_rpcs_in_flight_store(struct kobject *kobj,
@@ -139,13 +139,9 @@ static ssize_t max_dirty_mb_show(struct kobject *kobj,
 	struct obd_device *obd = container_of(kobj, struct obd_device,
 					      obd_kset.kobj);
 	struct client_obd *cli = &obd->u.cli;
-	unsigned long val;
 
-	spin_lock(&cli->cl_loi_list_lock);
-	val = PAGES_TO_MiB(cli->cl_dirty_max_pages);
-	spin_unlock(&cli->cl_loi_list_lock);
-
-	return scnprintf(buf, PAGE_SIZE, "%lu\n", val);
+	return scnprintf(buf, PAGE_SIZE, "%lu\n",
+			 PAGES_TO_MiB(cli->cl_dirty_max_pages));
 }
 
 static ssize_t max_dirty_mb_store(struct kobject *kobj,
@@ -252,7 +248,8 @@ static ssize_t cur_dirty_bytes_show(struct kobject *kobj,
 					      obd_kset.kobj);
 	struct client_obd *cli = &obd->u.cli;
 
-	return sprintf(buf, "%lu\n", cli->cl_dirty_pages << PAGE_SHIFT);
+	return scnprintf(buf, PAGE_SIZE, "%lu\n",
+			 cli->cl_dirty_pages << PAGE_SHIFT);
 }
 LUSTRE_RO_ATTR(cur_dirty_bytes);
 
@@ -264,7 +261,7 @@ static ssize_t cur_grant_bytes_show(struct kobject *kobj,
 					      obd_kset.kobj);
 	struct client_obd *cli = &obd->u.cli;
 
-	return sprintf(buf, "%lu\n", cli->cl_avail_grant);
+	return scnprintf(buf, PAGE_SIZE, "%lu\n", cli->cl_avail_grant);
 }
 
 static ssize_t cur_grant_bytes_store(struct kobject *kobj,
@@ -284,12 +281,8 @@ static ssize_t cur_grant_bytes_store(struct kobject *kobj,
 		return rc;
 
 	/* this is only for shrinking grant */
-	spin_lock(&cli->cl_loi_list_lock);
-	if (val >= cli->cl_avail_grant) {
-		spin_unlock(&cli->cl_loi_list_lock);
+	if (val >= cli->cl_avail_grant)
 		return -EINVAL;
-	}
-	spin_unlock(&cli->cl_loi_list_lock);
 
 	with_imp_locked(obd, imp, rc)
 		if (imp->imp_state == LUSTRE_IMP_FULL)
@@ -307,7 +300,7 @@ static ssize_t cur_lost_grant_bytes_show(struct kobject *kobj,
 					      obd_kset.kobj);
 	struct client_obd *cli = &obd->u.cli;
 
-	return sprintf(buf, "%lu\n", cli->cl_lost_grant);
+	return scnprintf(buf, PAGE_SIZE, "%lu\n", cli->cl_lost_grant);
 }
 LUSTRE_RO_ATTR(cur_lost_grant_bytes);
 
-- 
1.8.3.1

  parent reply	other threads:[~2020-10-06  0:06 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-06  0:05 [lustre-devel] [PATCH 00/42] lustre: OpenSFS backport for Oct 4 2020 James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 01/42] lustre: ptlrpc: don't require CONFIG_CRYPTO_CRC32 James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 02/42] lustre: dom: lock cancel to drop pages James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 03/42] lustre: sec: use memchr_inv() to check if page is zero James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 04/42] lustre: mdc: fix lovea for replay James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 05/42] lustre: llite: add test to check client deadlock selinux James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 06/42] lnet: use init_wait(), not init_waitqueue_entry() James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 07/42] lustre: lov: make various lov_object.c function static James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 08/42] lustre: llite: return -ENODATA if no default layout James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 09/42] lnet: libcfs: don't save journal_info in dumplog thread James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 10/42] lustre: ldlm: lru code cleanup James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 11/42] lustre: ldlm: cancel LRU improvement James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 12/42] lnet: Do not set preferred NI for MR peer James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 13/42] lustre: ptlrpc: prefer crc32_le() over CryptoAPI James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 14/42] lnet: call event handlers without res_lock James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 15/42] lnet: Conditionally attach rspt in LNetPut & LNetGet James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 16/42] lustre: llite: reuse same cl_dio_aio for one IO James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 17/42] lustre: llite: move iov iter forward by ourself James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 18/42] lustre: llite: report client stats sumsq James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 19/42] lnet: Support checking for MD leaks James Simmons
2020-10-06  0:05 ` [lustre-devel] [PATCH 20/42] lnet: don't read debugfs lnet stats when shutting down James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 21/42] lnet: Loosen restrictions on LNet Health params James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 22/42] lnet: Fix reference leak in lnet_select_pathway James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 23/42] lustre: llite: prune invalid dentries James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 24/42] lnet: Do not overwrite destination when routing James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 25/42] lustre: lov: don't use inline for operations functions James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 26/42] lustre: osc: don't allow negative grants James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 27/42] lustre: mgc: Use IR for client->MDS/OST connections James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 28/42] lustre: ldlm: don't use a locks without l_ast_data James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 29/42] lustre: lov: discard unused lov_dump_lmm* functions James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 30/42] lustre: lov: guard against class_exp2obd() returning NULL James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 31/42] lustre: clio: don't call aio_complete() in lustre upon errors James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 32/42] lustre: llite: it_lock_bits should be bit-wise tested James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 33/42] lustre: ldlm: control lru_size for extent lock James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 34/42] lustre: ldlm: pool fixes James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 35/42] lustre: ldlm: pool recalc forceful call James Simmons
2020-10-06  0:06 ` James Simmons [this message]
2020-10-06  0:06 ` [lustre-devel] [PATCH 37/42] lustre: osc: Do ELC on locks with no OSC object James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 38/42] lnet: deadlock on LNet shutdown James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 39/42] lustre: update version to 2.13.56 James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 40/42] lustre: llite: increase readahead default values James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 41/42] lustre: obdclass: don't initialize obj for zero FID James Simmons
2020-10-06  0:06 ` [lustre-devel] [PATCH 42/42] lustre: obdclass: fixes and improvements for jobid James Simmons

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=1601942781-24950-37-git-send-email-jsimmons@infradead.org \
    --to=jsimmons@infradead.org \
    --cc=lustre-devel@lists.lustre.org \
    --subject='Re: [lustre-devel] [PATCH 36/42] lustre: don'\''t take spinlock to read a '\''long'\''.' \
    /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

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).