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Fri, 08 Aug 2025 04:30:22 -0700 (PDT) From: Abinash Singh To: dlemoal@kernel.org Cc: James.Bottomley@HansenPartnership.com, abinashsinghlalotra@gmail.com, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, martin.petersen@oracle.com Subject: [PATCH v3] scsi: sd: Fix build warning in sd_revalidate_disk() Date: Fri, 8 Aug 2025 17:00:19 +0530 Message-ID: <20250808113019.20177-2-abinashsinghlalotra@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250808113019.20177-1-abinashsinghlalotra@gmail.com> References: <5cfefec0-b64b-4f96-a943-4de3205d3c50@kernel.org> <20250808113019.20177-1-abinashsinghlalotra@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable A build warning was triggered due to excessive stack usage in sd_revalidate_disk(): drivers/scsi/sd.c: In function =E2=80=98sd_revalidate_disk.isra=E2=80=99: drivers/scsi/sd.c:3824:1: warning: the frame size of 1160 bytes is larger t= han 1024 bytes [-Wframe-larger-than=3D] This is caused by a large local struct queue_limits (~400B) allocated on the stack. Replacing it with a heap allocation using kmalloc() significantly reduces frame usage. Kernel stack is limited (~8 KB), and allocating large structs on the stack is discouraged. As the function already performs heap allocations (e.g. for buffer), this change fits well. Signed-off-by: Abinash Singh --- Hi , As I mentioned in v2,.. this is the corresponding v3 of that. Only difference is in using __free() attribute Please infor me which one is better. changelog v2->v3: used __free(kfree) attribute. no extra goto statements (i.e `free_lim`) lim was initialized to NULL because there is a return path before its allocation. Early exit will pass uninitlized pointer to `kfree`. We could move the allocation earlier, before this check: if (!scsi_device_online(sdp)) goto out; However, doing so would result in unnecessary allocation if the device is not online, leading to wasted resources. Thanks, --- drivers/scsi/sd.c | 42 +++++++++++++++++++++++++----------------- 1 file changed, 25 insertions(+), 17 deletions(-) diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 4a68b2ab2804..50abbab7e27a 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -34,6 +34,7 @@ */ =20 #include +#include #include #include #include @@ -3696,7 +3697,7 @@ static int sd_revalidate_disk(struct gendisk *disk) struct scsi_disk *sdkp =3D scsi_disk(disk); struct scsi_device *sdp =3D sdkp->device; sector_t old_capacity =3D sdkp->capacity; - struct queue_limits lim; + struct queue_limits *lim __free(kfree) =3D NULL; unsigned char *buffer; unsigned int dev_max; int err; @@ -3711,6 +3712,13 @@ static int sd_revalidate_disk(struct gendisk *disk) if (!scsi_device_online(sdp)) goto out; =20 + lim =3D kmalloc(sizeof(*lim), GFP_KERNEL); + if (!lim) { + sd_printk(KERN_WARNING, sdkp, + "sd_revalidate_disk: Disk limit allocation failure.\n"); + goto out; + } + buffer =3D kmalloc(SD_BUF_SIZE, GFP_KERNEL); if (!buffer) { sd_printk(KERN_WARNING, sdkp, "sd_revalidate_disk: Memory " @@ -3720,14 +3728,14 @@ static int sd_revalidate_disk(struct gendisk *disk) =20 sd_spinup_disk(sdkp); =20 - lim =3D queue_limits_start_update(sdkp->disk->queue); + *lim =3D queue_limits_start_update(sdkp->disk->queue); =20 /* * Without media there is no reason to ask; moreover, some devices * react badly if we do. */ if (sdkp->media_present) { - sd_read_capacity(sdkp, &lim, buffer); + sd_read_capacity(sdkp, lim, buffer); /* * Some USB/UAS devices return generic values for mode pages * until the media has been accessed. Trigger a READ operation @@ -3741,17 +3749,17 @@ static int sd_revalidate_disk(struct gendisk *disk) * cause this to be updated correctly and any device which * doesn't support it should be treated as rotational. */ - lim.features |=3D (BLK_FEAT_ROTATIONAL | BLK_FEAT_ADD_RANDOM); + lim->features |=3D (BLK_FEAT_ROTATIONAL | BLK_FEAT_ADD_RANDOM); =20 if (scsi_device_supports_vpd(sdp)) { sd_read_block_provisioning(sdkp); - sd_read_block_limits(sdkp, &lim); + sd_read_block_limits(sdkp, lim); sd_read_block_limits_ext(sdkp); - sd_read_block_characteristics(sdkp, &lim); - sd_zbc_read_zones(sdkp, &lim, buffer); + sd_read_block_characteristics(sdkp, lim); + sd_zbc_read_zones(sdkp, lim, buffer); } =20 - sd_config_discard(sdkp, &lim, sd_discard_mode(sdkp)); + sd_config_discard(sdkp, lim, sd_discard_mode(sdkp)); =20 sd_print_capacity(sdkp, old_capacity); =20 @@ -3761,45 +3769,45 @@ static int sd_revalidate_disk(struct gendisk *disk) sd_read_app_tag_own(sdkp, buffer); sd_read_write_same(sdkp, buffer); sd_read_security(sdkp, buffer); - sd_config_protection(sdkp, &lim); + sd_config_protection(sdkp, lim); } =20 /* * We now have all cache related info, determine how we deal * with flush requests. */ - sd_set_flush_flag(sdkp, &lim); + sd_set_flush_flag(sdkp, lim); =20 /* Initial block count limit based on CDB TRANSFER LENGTH field size. */ dev_max =3D sdp->use_16_for_rw ? SD_MAX_XFER_BLOCKS : SD_DEF_XFER_BLOCKS; =20 /* Some devices report a maximum block count for READ/WRITE requests. */ dev_max =3D min_not_zero(dev_max, sdkp->max_xfer_blocks); - lim.max_dev_sectors =3D logical_to_sectors(sdp, dev_max); + lim->max_dev_sectors =3D logical_to_sectors(sdp, dev_max); =20 if (sd_validate_min_xfer_size(sdkp)) - lim.io_min =3D logical_to_bytes(sdp, sdkp->min_xfer_blocks); + lim->io_min =3D logical_to_bytes(sdp, sdkp->min_xfer_blocks); else - lim.io_min =3D 0; + lim->io_min =3D 0; =20 /* * Limit default to SCSI host optimal sector limit if set. There may be * an impact on performance for when the size of a request exceeds this * host limit. */ - lim.io_opt =3D sdp->host->opt_sectors << SECTOR_SHIFT; + lim->io_opt =3D sdp->host->opt_sectors << SECTOR_SHIFT; if (sd_validate_opt_xfer_size(sdkp, dev_max)) { - lim.io_opt =3D min_not_zero(lim.io_opt, + lim->io_opt =3D min_not_zero(lim->io_opt, logical_to_bytes(sdp, sdkp->opt_xfer_blocks)); } =20 sdkp->first_scan =3D 0; =20 set_capacity_and_notify(disk, logical_to_sectors(sdp, sdkp->capacity)); - sd_config_write_same(sdkp, &lim); + sd_config_write_same(sdkp, lim); kfree(buffer); =20 - err =3D queue_limits_commit_update_frozen(sdkp->disk->queue, &lim); + err =3D queue_limits_commit_update_frozen(sdkp->disk->queue, lim); if (err) return err; =20 --=20 2.50.1