Hi Dominique,
On 2018/7/17 19:56, Dominique Martinet wrote:
> piaojun wrote on Tue, Jul 17, 2018:
>> In p9_read_work(), we use spin_lock for client->lock, but misuse
>> spin_lock_irqsave for it in p9_fid_create(). As p9_client lock won't be
>> locked in irq context, so spin_lock is enough. And that will improve the
>> performance.
>
> (I didn't say in v1, but the commit message sounds a bit odd to me, if
> there is any other change to the patch could you please rephrase it a
> bit?)
Yes, I will rephrase it if there is any change to the patch.
>
>> Rebased on 9p-next.
>
> (Likewise, this should probably go below the '---' mark to not be in the
> final commit message, 9p-next does not make sense to linux as a whole)
>
Thanks for your suggestion.
>>
>> Signed-off-by: Jun Piao <piao...@huawei.com>
>
> Nitpicks aside this still looks good to me, I'm not expert in locking
> but I believe the conn_cancel stuff in trans_fd is called either from
> user context or workqueue which also is process context, while the rest
> comes from user context only.
>
> There *are* common functions called from interrupt context (I see:
> p9_tag_lookup, p9_client_cb, p9_parse_header) but luckily enough
> none of these take the lock.
>
> I'll give this one a little bit of time for others to review before
> picking it up, just in case, but will do if no-one complains.
>
>> ---
>> net/9p/client.c | 18 ++++++++----------
>> net/9p/trans_fd.c | 7 +++----
>> 2 files changed, 11 insertions(+), 14 deletions(-)
>>
>> diff --git a/net/9p/client.c b/net/9p/client.c
>> index 30f9aee..f6897ee 100644
>> --- a/net/9p/client.c
>> +++ b/net/9p/client.c
>> @@ -275,14 +275,14 @@ static struct p9_fcall *p9_fcall_alloc(int alloc_msize)
>> INIT_LIST_HEAD(&req->req_list);
>>
>> idr_preload(GFP_NOFS);
>> - spin_lock_irq(&c->lock);
>> + spin_lock(&c->lock);
>> if (type == P9_TVERSION)
>> tag = idr_alloc(&c->reqs, req, P9_NOTAG, P9_NOTAG + 1,
>> GFP_NOWAIT);
>> else
>> tag = idr_alloc(&c->reqs, req, 0, P9_NOTAG, GFP_NOWAIT);
>> req->tc->tag = tag;
>> - spin_unlock_irq(&c->lock);
>> + spin_unlock(&c->lock);
>> idr_preload_end();
>> if (tag < 0)
>> goto free;
>> @@ -328,13 +328,12 @@ struct p9_req_t *p9_tag_lookup(struct p9_client *c,
>> u16 tag)
>> */
>> static void p9_free_req(struct p9_client *c, struct p9_req_t *r)
>> {
>> - unsigned long flags;
>> u16 tag = r->tc->tag;
>>
>> p9_debug(P9_DEBUG_MUX, "clnt %p req %p tag: %d\n", c, r, tag);
>> - spin_lock_irqsave(&c->lock, flags);
>> + spin_lock(&c->lock);
>> idr_remove(&c->reqs, tag);
>> - spin_unlock_irqrestore(&c->lock, flags);
>> + spin_unlock(&c->lock);
>> kfree(r->tc);
>> kfree(r->rc);
>> kmem_cache_free(p9_req_cache, r);
>> @@ -846,10 +845,10 @@ static struct p9_fid *p9_fid_create(struct p9_client
>> *clnt)
>> fid->fid = 0;
>>
>> idr_preload(GFP_KERNEL);
>> - spin_lock_irq(&clnt->lock);
>> + spin_lock(&clnt->lock);
>> ret = idr_alloc_u32(&clnt->fids, fid, &fid->fid, P9_NOFID - 1,
>> GFP_NOWAIT);
>> - spin_unlock_irq(&clnt->lock);
>> + spin_unlock(&clnt->lock);
>> idr_preload_end();
>>
>> if (!ret)
>> @@ -862,13 +861,12 @@ static struct p9_fid *p9_fid_create(struct p9_client
>> *clnt)
>> static void p9_fid_destroy(struct p9_fid *fid)
>> {
>> struct p9_client *clnt;
>> - unsigned long flags;
>>
>> p9_debug(P9_DEBUG_FID, "fid %d\n", fid->fid);
>> clnt = fid->clnt;
>> - spin_lock_irqsave(&clnt->lock, flags);
>> + spin_lock(&clnt->lock);
>> idr_remove(&clnt->fids, fid->fid);
>> - spin_unlock_irqrestore(&clnt->lock, flags);
>> + spin_unlock(&clnt->lock);
>> kfree(fid->rdir);
>> kfree(fid);
>> }
>> diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
>> index bf459ee..94ef685 100644
>> --- a/net/9p/trans_fd.c
>> +++ b/net/9p/trans_fd.c
>> @@ -197,15 +197,14 @@ static void p9_mux_poll_stop(struct p9_conn *m)
>> static void p9_conn_cancel(struct p9_conn *m, int err)
>> {
>> struct p9_req_t *req, *rtmp;
>> - unsigned long flags;
>> LIST_HEAD(cancel_list);
>>
>> p9_debug(P9_DEBUG_ERROR, "mux %p err %d\n", m, err);
>>
>> - spin_lock_irqsave(&m->client->lock, flags);
>> + spin_lock(&m->client->lock);
>>
>> if (m->err) {
>> - spin_unlock_irqrestore(&m->client->lock, flags);
>> + spin_unlock(&m->client->lock);
>> return;
>> }
>>
>> @@ -217,7 +216,7 @@ static void p9_conn_cancel(struct p9_conn *m, int err)
>> list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
>> list_move(&req->req_list, &cancel_list);
>> }
>> - spin_unlock_irqrestore(&m->client->lock, flags);
>> + spin_unlock(&m->client->lock);
>>
>> list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
>> p9_debug(P9_DEBUG_ERROR, "call back req %p\n", req);
>> --
>
