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Thu, 23 Oct 2025 05:53:42 +0000 (GMT) Message-ID: <0baa8908-529b-45e9-87b5-3c229aecdc52@linux.ibm.com> Date: Thu, 23 Oct 2025 11:23:40 +0530 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] block: unify elevator tags and type xarrays into struct elv_change_ctx To: Ming Lei Cc: linux-block@vger.kernel.org, hch@lst.de, yukuai1@huaweicloud.com, axboe@kernel.dk, yi.zhang@redhat.com, czhong@redhat.com, gjoyce@ibm.com References: <20251016053057.3457663-1-nilay@linux.ibm.com> <20251016053057.3457663-2-nilay@linux.ibm.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDE4MDAyMiBTYWx0ZWRfX1iCkb+mDGxAA gqHqsTqzHS7WmyrG3gEi1JZLHF8QY6/N+EDoWHJfQ38vEM9JEFUPsrdaca8cjAu7DEbPCFwzLuF EkJTS1+PV29wXY+1nPccaIA/ODB5z3UqU8ekVSAOzXqWxzOkc2pw2Y/5xiaILXSyviSiBhaiXlA Ney4blYVJEPftdaOSqiBfJr44TeClGWjhqv3QIeWGDScvgjn8AnBykBWsAfmhkDvDPGL8BE84Vi pFPORfDUPRqlVNEBC/k7c8sXN+ZOYZwRi1MWu87ooyKHwQn08HZsQuW663JfPY7e/c3N9GYriYM tZdc3pg+FjodgGuQYUrWTAOfEyXt/lk0yM9q7rh3KXI+nH7Ig4eL0Vb8eNBw+wdVIhOXk3Z0HgK kvI6hlxzgWMakcoutgpo9lalnyz9aw== X-Authority-Analysis: v=2.4 cv=OrVCCi/t c=1 sm=1 tr=0 ts=68f9c2eb cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=x6icFKpwvdMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=CA3WoMP3M7Mil-wWCVUA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=cPQSjfK2_nFv0Q5t_7PE:22 X-Proofpoint-GUID: mGWyFKvd2aR1DJjOqxoYNc-_21d69u0s X-Proofpoint-ORIG-GUID: mGWyFKvd2aR1DJjOqxoYNc-_21d69u0s X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-22_08,2025-10-22_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 adultscore=0 priorityscore=1501 spamscore=0 phishscore=0 clxscore=1015 bulkscore=0 malwarescore=0 lowpriorityscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510020000 definitions=main-2510180022 On 10/22/25 9:41 AM, Ming Lei wrote: > On Thu, Oct 16, 2025 at 11:00:47AM +0530, Nilay Shroff wrote: >> >> +int blk_mq_alloc_sched_ctx_batch(struct xarray *elv_tbl, >> + struct blk_mq_tag_set *set) >> +{ >> + struct request_queue *q; >> + struct elv_change_ctx *ctx; >> + >> + lockdep_assert_held_write(&set->update_nr_hwq_lock); >> + >> + list_for_each_entry(q, &set->tag_list, tag_set_list) { >> + ctx = kzalloc(sizeof(struct elv_change_ctx), GFP_KERNEL); >> + if (!ctx) >> + goto out_unwind; >> + >> + if (xa_insert(elv_tbl, q->id, ctx, GFP_KERNEL)) { >> + kfree(ctx); >> + goto out_unwind; >> + } >> + } >> + return 0; >> +out_unwind: >> + list_for_each_entry_continue_reverse(q, &set->tag_list, tag_set_list) { >> + ctx = xa_load(elv_tbl, q->id); >> + kfree(ctx); >> + } > > No need to unwind, you can let blk_mq_free_sched_ctx_batch cover cleanup from > callsite. Yes, that makes sense. I’ll drop the unwind logic and rely on blk_mq_free_sched_ctx_batch() for cleanup at the callsite in the next version. > Not mention you leave freed `ctx` into xarray, which is fragile. Good catch! Removing the unwind block will naturally avoid that issue as well. >> @@ -530,12 +563,12 @@ int blk_mq_alloc_sched_tags_batch(struct xarray *et_table, >> out_unwind: >> list_for_each_entry_continue_reverse(q, &set->tag_list, tag_set_list) { >> if (q->elevator) { >> - et = xa_load(et_table, q->id); >> - if (et) >> - blk_mq_free_sched_tags(et, set); >> + ctx = xa_load(elv_tbl, q->id); >> + if (ctx && ctx->et) >> + blk_mq_free_sched_tags(ctx->et, set); > > please clear ctx->et when it is freed. Ack, will fix it in next version. >> +static inline void blk_mq_free_sched_ctx_batch(struct xarray *elv_tbl) >> +{ >> + unsigned long i; >> + struct elv_change_ctx *ctx; >> + >> + xa_for_each(elv_tbl, i, ctx) { >> + xa_erase(elv_tbl, i); >> + kfree(ctx); >> + } >> +} >> + > > It could be more readable to move blk_mq_free_sched_ctx_batch() with > blk_mq_alloc_sched_ctx_batch() together. > Agreed — I’ll move blk_mq_free_sched_ctx_batch() next to blk_mq_alloc_sched_ctx_batch() for better readability. Thanks, --Nilay