kernel/linux.git/drivers/s390, branch v4.4.171

scsi: zfcp: fix posting too many status read buffers leading to adapter shutdown

2019-01-13T09:05:32+00:00

commit 60a161b7e5b2a252ff0d4c622266a7d8da1120ce upstream. Suppose adapter (open) recovery is between opened QDIO queues and before (the end of) initial posting of status read buffers (SRBs). This time window can be seconds long due to FSF_PROT_HOST_CONNECTION_INITIALIZING causing by design looping with exponential increase sleeps in the function performing exchange config data during recovery [zfcp_erp_adapter_strat_fsf_xconf()]. Recovery triggered by local link up. Suppose an event occurs for which the FCP channel would send an unsolicited notification to zfcp by means of a previously posted SRB. We saw it with local cable pull (link down) in multi-initiator zoning with multiple NPIV-enabled subchannels of the same shared FCP channel. As soon as zfcp_erp_adapter_strategy_open_fsf() starts posting the initial status read buffers from within the adapter's ERP thread, the channel does send an unsolicited notification. Since v2.6.27 commit d26ab06ede83 ("[SCSI] zfcp: receiving an unsolicted status can lead to I/O stall"), zfcp_fsf_status_read_handler() schedules adapter->stat_work to re-fill the just consumed SRB from a work item. Now the ERP thread and the work item post SRBs in parallel. Both contexts call the helper function zfcp_status_read_refill(). The tracking of missing (to be posted / re-filled) SRBs is not thread-safe due to separate atomic_read() and atomic_dec(), in order to depend on posting success. Hence, both contexts can see atomic_read(&adapter->stat_miss) == 1. One of the two contexts posts one too many SRB. Zfcp gets QDIO_ERROR_SLSB_STATE on the output queue (trace tag "qdireq1") leading to zfcp_erp_adapter_shutdown() in zfcp_qdio_handler_error(). An obvious and seemingly clean fix would be to schedule stat_work from the ERP thread and wait for it to finish. This would serialize all SRB re-fills. However, we already have another work item wait on the ERP thread: adapter->scan_work runs zfcp_fc_scan_ports() which calls zfcp_fc_eval_gpn_ft(). The latter calls zfcp_erp_wait() to wait for all the open port recoveries during zfcp auto port scan, but in fact it waits for any pending recovery including an adapter recovery. This approach leads to a deadlock. [see also v3.19 commit 18f87a67e6d6 ("zfcp: auto port scan resiliency"); v2.6.37 commit d3e1088d6873 ("[SCSI] zfcp: No ERP escalation on gpn_ft eval"); v2.6.28 commit fca55b6fb587 ("[SCSI] zfcp: fix deadlock between wq triggered port scan and ERP") fixing v2.6.27 commit c57a39a45a76 ("[SCSI] zfcp: wait until adapter is finished with ERP during auto-port"); v2.6.27 commit cc8c282963bd ("[SCSI] zfcp: Automatically attach remote ports")] Instead make the accounting of missing SRBs atomic for parallel execution in both the ERP thread and adapter->stat_work. Signed-off-by: Steffen Maier Fixes: d26ab06ede83 ("[SCSI] zfcp: receiving an unsolicted status can lead to I/O stall") Cc: #2.6.27+ Reviewed-by: Jens Remus Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman

virtio/s390: fix race in ccw_io_helper()

2018-12-13T08:21:36+00:00

commit 78b1a52e05c9db11d293342e8d6d8a230a04b4e7 upstream. While ccw_io_helper() seems like intended to be exclusive in a sense that it is supposed to facilitate I/O for at most one thread at any given time, there is actually nothing ensuring that threads won't pile up at vcdev->wait_q. If they do, all threads get woken up and see the status that belongs to some other request than their own. This can lead to bugs. For an example see: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1788432 This race normally does not cause any problems. The operations provided by struct virtio_config_ops are usually invoked in a well defined sequence, normally don't fail, and are normally used quite infrequent too. Yet, if some of the these operations are directly triggered via sysfs attributes, like in the case described by the referenced bug, userspace is given an opportunity to force races by increasing the frequency of the given operations. Let us fix the problem by ensuring, that for each device, we finish processing the previous request before starting with a new one. Signed-off-by: Halil Pasic Reported-by: Colin Ian King Cc: stable@vger.kernel.org Message-Id: <20180925121309.58524-3-pasic@linux.ibm.com> Signed-off-by: Cornelia Huck Signed-off-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman

virtio/s390: avoid race on vcdev->config

2018-12-13T08:21:36+00:00

commit 2448a299ec416a80f699940a86f4a6d9a4f643b1 upstream. Currently we have a race on vcdev->config in virtio_ccw_get_config() and in virtio_ccw_set_config(). This normally does not cause problems, as these are usually infrequent operations. However, for some devices writing to/reading from the config space can be triggered through sysfs attributes. For these, userspace can force the race by increasing the frequency. Signed-off-by: Halil Pasic Cc: stable@vger.kernel.org Message-Id: <20180925121309.58524-2-pasic@linux.ibm.com> Signed-off-by: Cornelia Huck Signed-off-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman

s390/qeth: fix length check in SNMP processing

2018-12-13T08:21:26+00:00

[ Upstream commit 9a764c1e59684c0358e16ccaafd870629f2cfe67 ] The response for a SNMP request can consist of multiple parts, which the cmd callback stages into a kernel buffer until all parts have been received. If the callback detects that the staging buffer provides insufficient space, it bails out with error. This processing is buggy for the first part of the response - while it initially checks for a length of 'data_len', it later copies an additional amount of 'offsetof(struct qeth_snmp_cmd, data)' bytes. Fix the calculation of 'data_len' for the first part of the response. This also nicely cleans up the memcpy code. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Julian Wiedmann Reviewed-by: Ursula Braun Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

s390/qeth: don't dump past end of unknown HW header

2018-10-10T06:52:12+00:00

[ Upstream commit 0ac1487c4b2de383b91ecad1be561b8f7a2c15f4 ] For inbound data with an unsupported HW header format, only dump the actual HW header. We have no idea how much payload follows it, and what it contains. Worst case, we dump past the end of the Inbound Buffer and access whatever is located next in memory. Signed-off-by: Julian Wiedmann Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

s390/qeth: reset layer2 attribute on layer switch

2018-09-26T06:35:06+00:00

[ Upstream commit 70551dc46ffa3555a0b5f3545b0cd87ab67fd002 ] After the subdriver's remove() routine has completed, the card's layer mode is undetermined again. Reflect this in the layer2 field. If qeth_dev_layer2_store() hits an error after remove() was called, the card _always_ requires a setup(), even if the previous layer mode is requested again. But qeth_dev_layer2_store() bails out early if the requested layer mode still matches the current one. So unless we reset the layer2 field, re-probing the card back to its previous mode is currently not possible. Signed-off-by: Julian Wiedmann Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

s390/qeth: fix race in used-buffer accounting

2018-09-26T06:35:06+00:00

[ Upstream commit a702349a4099cd5a7bab0904689d8e0bf8dcd622 ] By updating q->used_buffers only _after_ do_QDIO() has completed, there is a potential race against the buffer's TX completion. In the unlikely case that the TX completion path wins, qeth_qdio_output_handler() would decrement the counter before qeth_flush_buffers() even incremented it. Signed-off-by: Julian Wiedmann Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

s390/dasd: fix hanging offline processing due to canceled worker

2018-09-15T07:40:39+00:00

[ Upstream commit 669f3765b755fd8739ab46ce3a9c6292ce8b3d2a ] During offline processing two worker threads are canceled without freeing the device reference which leads to a hanging offline process. Reviewed-by: Jan Hoeppner Signed-off-by: Stefan Haberland Signed-off-by: Martin Schwidefsky Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

s390/qdio: reset old sbal_state flags

2018-09-05T07:18:40+00:00

commit 64e03ff72623b8c2ea89ca3cb660094e019ed4ae upstream. When allocating a new AOB fails, handle_outbound() is still capable of transmitting the selected buffer (just without async completion). But if a previous transfer on this queue slot used async completion, its sbal_state flags field is still set to QDIO_OUTBUF_STATE_FLAG_PENDING. So when the upper layer driver sees this stale flag, it expects an async completion that never happens. Fix this by unconditionally clearing the flags field. Fixes: 104ea556ee7f ("qdio: support asynchronous delivery of storage blocks") Cc: #v3.2+ Signed-off-by: Julian Wiedmann Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

scsi: zfcp: fix missing REC trigger trace on enqueue without ERP thread

2018-07-03T09:21:31+00:00

commit 6a76550841d412330bd86aed3238d1888ba70f0e upstream. Example trace record formatted with zfcpdbf from s390-tools: Timestamp : ... Area : REC Subarea : 00 Level : 1 Exception : - CPU ID : .. Caller : 0x... Record ID : 1 ZFCP_DBF_REC_TRIG Tag : ....... LUN : 0x... WWPN : 0x... D_ID : 0x... Adapter status : 0x... Port status : 0x... LUN status : 0x... Ready count : 0x... Running count : 0x... ERP want : 0x0. ZFCP_ERP_ACTION_REOPEN_... ERP need : 0xc0 ZFCP_ERP_ACTION_NONE Signed-off-by: Steffen Maier Cc: #2.6.38+ Reviewed-by: Benjamin Block Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman