From: Zhen Lei <thunder.leizhen@huawei.com> To: Oliver O'Halloran <oohall@gmail.com>, Dan Williams <dan.j.williams@intel.com>, Vishal Verma <vishal.l.verma@intel.com>, "Dave Jiang" <dave.jiang@intel.com>, Ira Weiny <ira.weiny@intel.com>, Markus Elfring <Markus.Elfring@web.de>, linux-nvdimm <linux-nvdimm@lists.01.org>, linux-kernel <linux-kernel@vger.kernel.org> Cc: Zhen Lei <thunder.leizhen@huawei.com>, Libin <huawei.libin@huawei.com>, Kefeng Wang <wangkefeng.wang@huawei.com> Subject: [PATCH v2 2/2] libnvdimm/badrange: eliminate a meaningless spinlock operation Date: Sat, 19 Sep 2020 18:45:46 +0800 [thread overview] Message-ID: <20200919104546.3848-3-thunder.leizhen@huawei.com> (raw) In-Reply-To: <20200919104546.3848-1-thunder.leizhen@huawei.com> badrange_add() take the lock "badrange->lock", but it's released immediately in add_badrange(), protect nothing. The pseudo code is as follows: In badrange_add(): spin_lock(&badrange->lock); <--------------- rc = add_badrange(badrange, addr, length); | In add_badrange(): | //do nothing | spin_unlock(&badrange->lock); <--------------- bre_new = kzalloc(sizeof(*bre_new), GFP_KERNEL); spin_lock(&badrange->lock); <--- lock again This lock/unlock operation is meaningless. Because the static function add_badrange() is only called by badrange_add(), so move its content into badrange_add() then delete it. By the way, move "kfree(bre_new)" out of the lock protection, it really doesn't need. Fixes: b3b454f694db ("libnvdimm: fix clear poison locking with spinlock ...") Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> --- drivers/nvdimm/badrange.c | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-) diff --git a/drivers/nvdimm/badrange.c b/drivers/nvdimm/badrange.c index 9fdba8c43e8605e..7f78b659057902d 100644 --- a/drivers/nvdimm/badrange.c +++ b/drivers/nvdimm/badrange.c @@ -45,12 +45,12 @@ static int alloc_and_append_badrange_entry(struct badrange *badrange, return 0; } -static int add_badrange(struct badrange *badrange, u64 addr, u64 length) +int badrange_add(struct badrange *badrange, u64 addr, u64 length) { struct badrange_entry *bre, *bre_new; - spin_unlock(&badrange->lock); bre_new = kzalloc(sizeof(*bre_new), GFP_KERNEL); + spin_lock(&badrange->lock); /* @@ -63,6 +63,7 @@ static int add_badrange(struct badrange *badrange, u64 addr, u64 length) /* If length has changed, update this list entry */ if (bre->length != length) bre->length = length; + spin_unlock(&badrange->lock); kfree(bre_new); return 0; } @@ -72,22 +73,15 @@ static int add_badrange(struct badrange *badrange, u64 addr, u64 length) * as any overlapping ranges will get resolved when the list is consumed * and converted to badblocks */ - if (!bre_new) + if (!bre_new) { + spin_unlock(&badrange->lock); return -ENOMEM; - append_badrange_entry(badrange, bre_new, addr, length); - - return 0; -} - -int badrange_add(struct badrange *badrange, u64 addr, u64 length) -{ - int rc; + } - spin_lock(&badrange->lock); - rc = add_badrange(badrange, addr, length); + append_badrange_entry(badrange, bre_new, addr, length); spin_unlock(&badrange->lock); - return rc; + return 0; } EXPORT_SYMBOL_GPL(badrange_add); -- 1.8.3 _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
WARNING: multiple messages have this Message-ID (diff)
From: Zhen Lei <thunder.leizhen@huawei.com> To: Oliver O'Halloran <oohall@gmail.com>, Dan Williams <dan.j.williams@intel.com>, Vishal Verma <vishal.l.verma@intel.com>, "Dave Jiang" <dave.jiang@intel.com>, Ira Weiny <ira.weiny@intel.com>, Markus Elfring <Markus.Elfring@web.de>, linux-nvdimm <linux-nvdimm@lists.01.org>, linux-kernel <linux-kernel@vger.kernel.org> Cc: Zhen Lei <thunder.leizhen@huawei.com>, Libin <huawei.libin@huawei.com>, Kefeng Wang <wangkefeng.wang@huawei.com> Subject: [PATCH v2 2/2] libnvdimm/badrange: eliminate a meaningless spinlock operation Date: Sat, 19 Sep 2020 18:45:46 +0800 [thread overview] Message-ID: <20200919104546.3848-3-thunder.leizhen@huawei.com> (raw) In-Reply-To: <20200919104546.3848-1-thunder.leizhen@huawei.com> badrange_add() take the lock "badrange->lock", but it's released immediately in add_badrange(), protect nothing. The pseudo code is as follows: In badrange_add(): spin_lock(&badrange->lock); <--------------- rc = add_badrange(badrange, addr, length); | In add_badrange(): | //do nothing | spin_unlock(&badrange->lock); <--------------- bre_new = kzalloc(sizeof(*bre_new), GFP_KERNEL); spin_lock(&badrange->lock); <--- lock again This lock/unlock operation is meaningless. Because the static function add_badrange() is only called by badrange_add(), so move its content into badrange_add() then delete it. By the way, move "kfree(bre_new)" out of the lock protection, it really doesn't need. Fixes: b3b454f694db ("libnvdimm: fix clear poison locking with spinlock ...") Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> --- drivers/nvdimm/badrange.c | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-) diff --git a/drivers/nvdimm/badrange.c b/drivers/nvdimm/badrange.c index 9fdba8c43e8605e..7f78b659057902d 100644 --- a/drivers/nvdimm/badrange.c +++ b/drivers/nvdimm/badrange.c @@ -45,12 +45,12 @@ static int alloc_and_append_badrange_entry(struct badrange *badrange, return 0; } -static int add_badrange(struct badrange *badrange, u64 addr, u64 length) +int badrange_add(struct badrange *badrange, u64 addr, u64 length) { struct badrange_entry *bre, *bre_new; - spin_unlock(&badrange->lock); bre_new = kzalloc(sizeof(*bre_new), GFP_KERNEL); + spin_lock(&badrange->lock); /* @@ -63,6 +63,7 @@ static int add_badrange(struct badrange *badrange, u64 addr, u64 length) /* If length has changed, update this list entry */ if (bre->length != length) bre->length = length; + spin_unlock(&badrange->lock); kfree(bre_new); return 0; } @@ -72,22 +73,15 @@ static int add_badrange(struct badrange *badrange, u64 addr, u64 length) * as any overlapping ranges will get resolved when the list is consumed * and converted to badblocks */ - if (!bre_new) + if (!bre_new) { + spin_unlock(&badrange->lock); return -ENOMEM; - append_badrange_entry(badrange, bre_new, addr, length); - - return 0; -} - -int badrange_add(struct badrange *badrange, u64 addr, u64 length) -{ - int rc; + } - spin_lock(&badrange->lock); - rc = add_badrange(badrange, addr, length); + append_badrange_entry(badrange, bre_new, addr, length); spin_unlock(&badrange->lock); - return rc; + return 0; } EXPORT_SYMBOL_GPL(badrange_add); -- 1.8.3
next prev parent reply other threads:[~2020-09-19 10:47 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-09-19 10:45 [PATCH v2 0/2] libnvdimm/badrange: simplify code Zhen Lei 2020-09-19 10:45 ` Zhen Lei 2020-09-19 10:45 ` [PATCH v2 1/2] libnvdimm/badrange: remove two redundant list_empty() branches Zhen Lei 2020-09-19 10:45 ` Zhen Lei 2020-09-19 10:45 ` Zhen Lei [this message] 2020-09-19 10:45 ` [PATCH v2 2/2] libnvdimm/badrange: eliminate a meaningless spinlock operation Zhen Lei
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=20200919104546.3848-3-thunder.leizhen@huawei.com \ --to=thunder.leizhen@huawei.com \ --cc=Markus.Elfring@web.de \ --cc=dan.j.williams@intel.com \ --cc=dave.jiang@intel.com \ --cc=huawei.libin@huawei.com \ --cc=ira.weiny@intel.com \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-nvdimm@lists.01.org \ --cc=oohall@gmail.com \ --cc=vishal.l.verma@intel.com \ --cc=wangkefeng.wang@huawei.com \ /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: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.