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Subject[PATCH 4.4 072/190] scsi: bnx2fc: fix race condition in bnx2fc_get_host_stats()
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Maurizio Lombardi <mlombard@redhat.com>


[ Upstream commit c2dd893a3b0772d1c680e109b9d5715d7f73022b ]

If multiple tasks attempt to read the stats, it may happen that the
start_req_done completion is re-initialized while still being used by
another task, causing a list corruption.

This patch fixes the bug by adding a mutex to serialize the calls to
bnx2fc_get_host_stats().

WARNING: at lib/list_debug.c:48 list_del+0x6e/0xa0() (Not tainted)
Hardware name: PowerEdge R820
list_del corruption. prev->next should be ffff882035627d90, but was ffff884069541588

Pid: 40267, comm: perl Not tainted 2.6.32-642.3.1.el6.x86_64 #1
Call Trace:
[<ffffffff8107c691>] ? warn_slowpath_common+0x91/0xe0
[<ffffffff8107c796>] ? warn_slowpath_fmt+0x46/0x60
[<ffffffff812ad16e>] ? list_del+0x6e/0xa0
[<ffffffff81547eed>] ? wait_for_common+0x14d/0x180
[<ffffffff8106c4a0>] ? default_wake_function+0x0/0x20
[<ffffffff81547fd3>] ? wait_for_completion_timeout+0x13/0x20
[<ffffffffa05410b1>] ? bnx2fc_get_host_stats+0xa1/0x280 [bnx2fc]
[<ffffffffa04cf630>] ? fc_stat_show+0x90/0xc0 [scsi_transport_fc]
[<ffffffffa04cf8b6>] ? show_fcstat_tx_frames+0x16/0x20 [scsi_transport_fc]
[<ffffffff8137c647>] ? dev_attr_show+0x27/0x50
[<ffffffff8113b9be>] ? __get_free_pages+0xe/0x50
[<ffffffff812170e1>] ? sysfs_read_file+0x111/0x200
[<ffffffff8119a305>] ? vfs_read+0xb5/0x1a0
[<ffffffff8119b0b6>] ? fget_light_pos+0x16/0x50
[<ffffffff8119a651>] ? sys_read+0x51/0xb0
[<ffffffff810ee1fe>] ? __audit_syscall_exit+0x25e/0x290
[<ffffffff8100b0d2>] ? system_call_fastpath+0x16/0x1b

Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Acked-by: Chad Dupuis <chad.dupuis@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/scsi/bnx2fc/bnx2fc.h | 1 +
drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 10 ++++++++--
2 files changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/scsi/bnx2fc/bnx2fc.h
+++ b/drivers/scsi/bnx2fc/bnx2fc.h
@@ -191,6 +191,7 @@ struct bnx2fc_hba {
struct bnx2fc_cmd_mgr *cmd_mgr;
spinlock_t hba_lock;
struct mutex hba_mutex;
+ struct mutex hba_stats_mutex;
unsigned long adapter_state;
#define ADAPTER_STATE_UP 0
#define ADAPTER_STATE_GOING_DOWN 1
--- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
@@ -641,15 +641,17 @@ static struct fc_host_statistics *bnx2fc
if (!fw_stats)
return NULL;

+ mutex_lock(&hba->hba_stats_mutex);
+
bnx2fc_stats = fc_get_host_stats(shost);

init_completion(&hba->stat_req_done);
if (bnx2fc_send_stat_req(hba))
- return bnx2fc_stats;
+ goto unlock_stats_mutex;
rc = wait_for_completion_timeout(&hba->stat_req_done, (2 * HZ));
if (!rc) {
BNX2FC_HBA_DBG(lport, "FW stat req timed out\n");
- return bnx2fc_stats;
+ goto unlock_stats_mutex;
}
BNX2FC_STATS(hba, rx_stat2, fc_crc_cnt);
bnx2fc_stats->invalid_crc_count += hba->bfw_stats.fc_crc_cnt;
@@ -671,6 +673,9 @@ static struct fc_host_statistics *bnx2fc

memcpy(&hba->prev_stats, hba->stats_buffer,
sizeof(struct fcoe_statistics_params));
+
+unlock_stats_mutex:
+ mutex_unlock(&hba->hba_stats_mutex);
return bnx2fc_stats;
}

@@ -1302,6 +1307,7 @@ static struct bnx2fc_hba *bnx2fc_hba_cre
}
spin_lock_init(&hba->hba_lock);
mutex_init(&hba->hba_mutex);
+ mutex_init(&hba->hba_stats_mutex);

hba->cnic = cnic;


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