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Wed, 5 Aug 2026 13:36:28 +0000 (GMT) From: Heiko Carstens To: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Niklas Schnelle , Gerd Bayer Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 2/3] s390/pci: Rework __zpci_event_availability() to remove conditional locking Date: Wed, 5 Aug 2026 15:36:26 +0200 Message-ID: <20260805133627.1216607-3-hca@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260805133627.1216607-1-hca@linux.ibm.com> References: <20260805133627.1216607-1-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA1MDEwNyBTYWx0ZWRfX9cMr9i9CvTzt BxuD9zzxf1O8zgX6AdO6NOuMTNOUT2r8hb15YPmo5YiDonC95LJ197Vf3Hh0P3mDRaL4hVlUfzO LYfEPmUDZk62HFqJM1ZiQMK5B2LZp5pRApdwET9UGhdxb1nSzu7+p23VV+7DBWLKcoRAPsEVO3d 898s74tl3lZvQCepWpKjmYDDlJWiz7OWADgWN8rtqim8hgNxFClS3l06UkGeNoV66/UYZHZFmg9 LqW4Ww+y1Djvu1gXoEv6HusM19+gev22506i+9aK5Q/v0M5oVZKPn88C0aj+T8/JEXITquvaksI JRGCI551nOwlLS6xlRVIxs+twWgXLowX9IG5M6N8UC/y2LeqDPKhaEc8dyvw9c6qkb+fKt4aY6K 1RPFdT18sJ7kdvrb9tK0QEdKbu4ewBGjK1YLQ2UQnZ9aAM6m0u0wHXHd3WDl4x7d69GgP2xgC2a iHCQ+j/eNmJRHc972Ow== X-Authority-Analysis: v=2.4 cv=WIFPmHsR c=1 sm=1 tr=0 ts=6a733c61 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VnNF1IyMAAAA:8 a=poQ7gJ9nSTMEjbrCJsEA:9 X-Proofpoint-GUID: uofeoXWfKrGKwuur-sd8Q6UBlYHCBy82 X-Proofpoint-ORIG-GUID: uofeoXWfKrGKwuur-sd8Q6UBlYHCBy82 X-Proofpoint-Spam-Info: AW1haW4tMjYwODA1MDEwNyBTYWx0ZWRfX2JOBVx6V/mlm P1a0RwRGT/94fDpDEPR8AciyEMelYsRz1qaOW64KHcdtc1/8o4kdgxgO6oV6nd528dU707glNPt rzj4NvMBocz58CeopQ7DWOCcJFXrzrU= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-05_04,2026-08-04_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 malwarescore=0 suspectscore=0 clxscore=1015 impostorscore=0 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608050107 Clang's compiler based static context analysis does not work with locks that are conditionally taken like in __zpci_event_availability(): arch/s390/pci/pci_event.c:402:10: warning: mutex 'get_zdev_by_fid(ccdf->fid).state_lock' is not held on every path through here [-Wthread-safety-analysis] Given that code which takes locks conditionally can be considered suboptimal rework __zpci_event_availability() to get rid of this. Signed-off-by: Heiko Carstens --- arch/s390/pci/pci_event.c | 162 ++++++++++++++++++++------------------ 1 file changed, 85 insertions(+), 77 deletions(-) diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c index bead4ed5d4ab..0a9eecb62bd1 100644 --- a/arch/s390/pci/pci_event.c +++ b/arch/s390/pci/pci_event.c @@ -387,98 +387,106 @@ static void zpci_event_reappear(struct zpci_dev *zdev) zpci_dbg(1, "rea fid:%x, fh:%x\n", zdev->fid, zdev->fh); } -static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf) +static bool zpci_event_avail_any_device(struct zpci_ccdf_avail *ccdf) { - struct zpci_dev *zdev = get_zdev_by_fid(ccdf->fid); - bool existing_zdev = !!zdev; - enum zpci_state state; + /* 0x0306 - No handle or fid stored */ + if (ccdf->pec != 0x0306) + return false; + /* 0x308 or 0x302 for multiple devices */ + zpci_remove_reserved_devices(); + zpci_scan_devices(); + return true; +} - zpci_dbg(3, "avl fid:%x, fh:%x, pec:%x\n", - ccdf->fid, ccdf->fh, ccdf->pec); - - if (existing_zdev) - mutex_lock(&zdev->state_lock); +static void zpci_event_avail_new_device(struct zpci_ccdf_avail *ccdf) +{ + struct zpci_dev *zdev; switch (ccdf->pec) { case 0x0301: /* Reserved|Standby -> Configured */ - if (!zdev) { - zdev = zpci_create_device(ccdf->fid, ccdf->fh, ZPCI_FN_STATE_CONFIGURED); - if (IS_ERR(zdev)) - break; - if (zpci_add_device(zdev)) { - kfree(zdev); - break; - } - } else { - if (zdev->state == ZPCI_FN_STATE_RESERVED) - zpci_event_reappear(zdev); - /* the configuration request may be stale */ - else if (zdev->state != ZPCI_FN_STATE_STANDBY) - break; - zdev->state = ZPCI_FN_STATE_CONFIGURED; + zdev = zpci_create_device(ccdf->fid, ccdf->fh, ZPCI_FN_STATE_CONFIGURED); + if (IS_ERR(zdev)) + break; + if (zpci_add_device(zdev)) { + kfree(zdev); + break; } zpci_scan_configured_device(zdev, ccdf->fh); break; case 0x0302: /* Reserved -> Standby */ - if (!zdev) { - zdev = zpci_create_device(ccdf->fid, ccdf->fh, ZPCI_FN_STATE_STANDBY); - if (IS_ERR(zdev)) - break; - if (zpci_add_device(zdev)) { - kfree(zdev); - break; - } - } else { - if (zdev->state == ZPCI_FN_STATE_RESERVED) - zpci_event_reappear(zdev); - zpci_update_fh(zdev, ccdf->fh); - } - break; - case 0x0303: /* Deconfiguration requested */ - if (zdev) { - /* The event may have been queued before we configured - * the device. - */ - if (zdev->state != ZPCI_FN_STATE_CONFIGURED) - break; - zpci_update_fh(zdev, ccdf->fh); - zpci_deconfigure_device(zdev); - } - break; - case 0x0304: /* Configured -> Standby|Reserved */ - if (zdev) { - /* The event may have been queued before we configured - * the device.: - */ - if (zdev->state == ZPCI_FN_STATE_CONFIGURED) - zpci_event_hard_deconfigured(zdev, ccdf->fh); - /* The 0x0304 event may immediately reserve the device */ - if (!clp_get_state(zdev->fid, &state) && - state == ZPCI_FN_STATE_RESERVED) { - zpci_device_reserved(zdev); - } - } - break; - case 0x0306: /* 0x308 or 0x302 for multiple devices */ - zpci_remove_reserved_devices(); - zpci_scan_devices(); - break; - case 0x0308: /* Standby -> Reserved */ - if (!zdev) + zdev = zpci_create_device(ccdf->fid, ccdf->fh, ZPCI_FN_STATE_STANDBY); + if (IS_ERR(zdev)) break; - zpci_device_reserved(zdev); - break; - default: + if (zpci_add_device(zdev)) { + kfree(zdev); + break; + } break; } - if (existing_zdev) { - mutex_unlock(&zdev->state_lock); - zpci_zdev_put(zdev); +} + +static void zpci_event_avail_existing_device(struct zpci_dev *zdev, struct zpci_ccdf_avail *ccdf) +{ + enum zpci_state state; + + switch (ccdf->pec) { + case 0x0301: /* Reserved|Standby -> Configured */ + if (zdev->state == ZPCI_FN_STATE_RESERVED) + zpci_event_reappear(zdev); + /* the configuration request may be stale */ + else if (zdev->state != ZPCI_FN_STATE_STANDBY) + break; + zdev->state = ZPCI_FN_STATE_CONFIGURED; + zpci_scan_configured_device(zdev, ccdf->fh); + break; + case 0x0302: /* Reserved -> Standby */ + if (zdev->state == ZPCI_FN_STATE_RESERVED) + zpci_event_reappear(zdev); + zpci_update_fh(zdev, ccdf->fh); + break; + case 0x0303: /* Deconfiguration requested */ + /* The event may have been queued before we configured + * the device. + */ + if (zdev->state != ZPCI_FN_STATE_CONFIGURED) + break; + zpci_update_fh(zdev, ccdf->fh); + zpci_deconfigure_device(zdev); + break; + case 0x0304: /* Configured -> Standby|Reserved */ + /* The event may have been queued before we configured + * the device.: + */ + if (zdev->state == ZPCI_FN_STATE_CONFIGURED) + zpci_event_hard_deconfigured(zdev, ccdf->fh); + /* The 0x0304 event may immediately reserve the device */ + if (!clp_get_state(zdev->fid, &state) && + state == ZPCI_FN_STATE_RESERVED) { + zpci_device_reserved(zdev); + } + break; + case 0x0308: /* Standby -> Reserved */ + zpci_device_reserved(zdev); + break; } } void zpci_event_availability(void *data) { - if (zpci_is_enabled()) - __zpci_event_availability(data); + struct zpci_ccdf_avail *ccdf = data; + struct zpci_dev *zdev; + + if (!zpci_is_enabled()) + return; + zpci_dbg(3, "avl fid:%x, fh:%x, pec:%x\n", + ccdf->fid, ccdf->fh, ccdf->pec); + if (zpci_event_avail_any_device(ccdf)) + return; + zdev = get_zdev_by_fid(ccdf->fid); + if (!zdev) + return zpci_event_avail_new_device(ccdf); + mutex_lock(&zdev->state_lock); + zpci_event_avail_existing_device(zdev, ccdf); + mutex_unlock(&zdev->state_lock); + zpci_zdev_put(zdev); } -- 2.53.0