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authorBenjamin Block <bblock@linux.ibm.com>2019-10-25 18:12:44 +0200
committerMartin K. Petersen <martin.petersen@oracle.com>2019-10-28 22:16:14 -0400
commit7e418833e68948cb9ed15262889173b7db2960cb (patch)
tree7a61e483bb7f76d6564a9fbfe6e18d6707af8133 /drivers/s390/scsi/zfcp_diag.c
parentscsi: zfcp: signal incomplete or error for sync exchange config/port data (diff)
downloadlinux-dev-7e418833e68948cb9ed15262889173b7db2960cb.tar.xz
linux-dev-7e418833e68948cb9ed15262889173b7db2960cb.zip
scsi: zfcp: diagnostics buffer caching and use for exchange port data
The FCP channel exposes two central interfaces to receive information about the local FCP-Adapter/-Port: Exchange Port and Exchange Config Data. Using these commands can negatively impact the adapter if we allow them to be sent at a very high rate. The later parts of this patchset will introduce new user-interfaces to receive more diagnostics from the adapter. To prevent any negative impact from using those, this patch adds a simple caching-mechanism that will prevent a malicious/faulty userspace-application from generating an abnormal high amount of Exchange Port/Config Data traffic. Relevant diagnostic data that is received via Exchange Config/Port Data is cached in buffers associated with the corresponding adapter-struct. Each buffer is associated with a timestamp that signals how old the data is, and, added via a following patch in this series, lets userspace-interfaces determine when the data is too old and needs to be updated. Buffer-updates are made during the normal response path of the corresponding command. With this patch only the output of the Exchange Port Data command is captured. Link: https://lore.kernel.org/r/054ca020ce0a53dc0d9176428bea373898944e6a.1572018130.git.bblock@linux.ibm.com Reviewed-by: Steffen Maier <maier@linux.ibm.com> Signed-off-by: Benjamin Block <bblock@linux.ibm.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/s390/scsi/zfcp_diag.c')
-rw-r--r--drivers/s390/scsi/zfcp_diag.c93
1 files changed, 93 insertions, 0 deletions
diff --git a/drivers/s390/scsi/zfcp_diag.c b/drivers/s390/scsi/zfcp_diag.c
new file mode 100644
index 000000000000..fa1b25f3ec3c
--- /dev/null
+++ b/drivers/s390/scsi/zfcp_diag.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * zfcp device driver
+ *
+ * Functions to handle diagnostics.
+ *
+ * Copyright IBM Corp. 2018
+ */
+
+#include <linux/spinlock.h>
+#include <linux/jiffies.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+
+#include "zfcp_diag.h"
+#include "zfcp_ext.h"
+#include "zfcp_def.h"
+
+/* Max age of data in a diagnostics buffer before it needs a refresh (in ms). */
+#define ZFCP_DIAG_MAX_AGE (5 * 1000)
+
+/**
+ * zfcp_diag_adapter_setup() - Setup storage for adapter diagnostics.
+ * @adapter: the adapter to setup diagnostics for.
+ *
+ * Creates the data-structures to store the diagnostics for an adapter. This
+ * overwrites whatever was stored before at &zfcp_adapter->diagnostics!
+ *
+ * Return:
+ * * 0 - Everyting is OK
+ * * -ENOMEM - Could not allocate all/parts of the data-structures;
+ * &zfcp_adapter->diagnostics remains unchanged
+ */
+int zfcp_diag_adapter_setup(struct zfcp_adapter *const adapter)
+{
+ struct zfcp_diag_adapter *diag;
+ struct zfcp_diag_header *hdr;
+
+ diag = kzalloc(sizeof(*diag), GFP_KERNEL);
+ if (diag == NULL)
+ return -ENOMEM;
+
+ /* setup header for port_data */
+ hdr = &diag->port_data.header;
+
+ spin_lock_init(&hdr->access_lock);
+ hdr->buffer = &diag->port_data.data;
+ hdr->buffer_size = sizeof(diag->port_data.data);
+ /* set the timestamp so that the first test on age will always fail */
+ hdr->timestamp = jiffies - msecs_to_jiffies(ZFCP_DIAG_MAX_AGE);
+
+ adapter->diagnostics = diag;
+ return 0;
+}
+
+/**
+ * zfcp_diag_adapter_free() - Frees all adapter diagnostics allocations.
+ * @adapter: the adapter whose diagnostic structures should be freed.
+ *
+ * Frees all data-structures in the given adapter that store diagnostics
+ * information. Can savely be called with partially setup diagnostics.
+ */
+void zfcp_diag_adapter_free(struct zfcp_adapter *const adapter)
+{
+ kfree(adapter->diagnostics);
+ adapter->diagnostics = NULL;
+}
+
+/**
+ * zfcp_diag_update_xdata() - Update a diagnostics buffer.
+ * @hdr: the meta data to update.
+ * @data: data to use for the update.
+ * @incomplete: flag stating whether the data in @data is incomplete.
+ */
+void zfcp_diag_update_xdata(struct zfcp_diag_header *const hdr,
+ const void *const data, const bool incomplete)
+{
+ const unsigned long capture_timestamp = jiffies;
+ unsigned long flags;
+
+ spin_lock_irqsave(&hdr->access_lock, flags);
+
+ /* make sure we never go into the past with an update */
+ if (!time_after_eq(capture_timestamp, hdr->timestamp))
+ goto out;
+
+ hdr->timestamp = capture_timestamp;
+ hdr->incomplete = incomplete;
+ memcpy(hdr->buffer, data, hdr->buffer_size);
+out:
+ spin_unlock_irqrestore(&hdr->access_lock, flags);
+}