From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Benjamin Block <bblock@linux.ibm.com>,
Jens Remus <jremus@linux.ibm.com>,
Steffen Maier <maier@linux.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.14 16/53] scsi: zfcp: fix GCC compiler warning emitted with -Wmaybe-uninitialized
Date: Mon, 5 Aug 2019 15:02:41 +0200 [thread overview]
Message-ID: <20190805124929.885292766@linuxfoundation.org> (raw)
In-Reply-To: <20190805124927.973499541@linuxfoundation.org>
[ Upstream commit 484647088826f2f651acbda6bcf9536b8a466703 ]
GCC v9 emits this warning:
CC drivers/s390/scsi/zfcp_erp.o
drivers/s390/scsi/zfcp_erp.c: In function 'zfcp_erp_action_enqueue':
drivers/s390/scsi/zfcp_erp.c:217:26: warning: 'erp_action' may be used uninitialized in this function [-Wmaybe-uninitialized]
217 | struct zfcp_erp_action *erp_action;
| ^~~~~~~~~~
This is a possible false positive case, as also documented in the GCC
documentations:
https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wmaybe-uninitialized
The actual code-sequence is like this:
Various callers can invoke the function below with the argument "want"
being one of:
ZFCP_ERP_ACTION_REOPEN_ADAPTER,
ZFCP_ERP_ACTION_REOPEN_PORT_FORCED,
ZFCP_ERP_ACTION_REOPEN_PORT, or
ZFCP_ERP_ACTION_REOPEN_LUN.
zfcp_erp_action_enqueue(want, ...)
...
need = zfcp_erp_required_act(want, ...)
need = want
...
maybe: need = ZFCP_ERP_ACTION_REOPEN_PORT
maybe: need = ZFCP_ERP_ACTION_REOPEN_ADAPTER
...
return need
...
zfcp_erp_setup_act(need, ...)
struct zfcp_erp_action *erp_action; // <== line 217
...
switch(need) {
case ZFCP_ERP_ACTION_REOPEN_LUN:
...
erp_action = &zfcp_sdev->erp_action;
WARN_ON_ONCE(erp_action->port != port); // <== access
...
break;
case ZFCP_ERP_ACTION_REOPEN_PORT:
case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:
...
erp_action = &port->erp_action;
WARN_ON_ONCE(erp_action->port != port); // <== access
...
break;
case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
...
erp_action = &adapter->erp_action;
WARN_ON_ONCE(erp_action->port != NULL); // <== access
...
break;
}
...
WARN_ON_ONCE(erp_action->adapter != adapter); // <== access
When zfcp_erp_setup_act() is called, 'need' will never be anything else
than one of the 4 possible enumeration-names that are used in the
switch-case, and 'erp_action' is initialized for every one of them, before
it is used. Thus the warning is a false positive, as documented.
We introduce the extra if{} in the beginning to create an extra code-flow,
so the compiler can be convinced that the switch-case will never see any
other value.
BUG_ON()/BUG() is intentionally not used to not crash anything, should
this ever happen anyway - right now it's impossible, as argued above; and
it doesn't introduce a 'default:' switch-case to retain warnings should
'enum zfcp_erp_act_type' ever be extended and no explicit case be
introduced. See also v5.0 commit 399b6c8bc9f7 ("scsi: zfcp: drop old
default switch case which might paper over missing case").
Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/s390/scsi/zfcp_erp.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index 6d5065f679acf..64d70de98cdb6 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -11,6 +11,7 @@
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/kthread.h>
+#include <linux/bug.h>
#include "zfcp_ext.h"
#include "zfcp_reqlist.h"
@@ -245,6 +246,12 @@ static struct zfcp_erp_action *zfcp_erp_setup_act(int need, u32 act_status,
struct zfcp_erp_action *erp_action;
struct zfcp_scsi_dev *zfcp_sdev;
+ if (WARN_ON_ONCE(need != ZFCP_ERP_ACTION_REOPEN_LUN &&
+ need != ZFCP_ERP_ACTION_REOPEN_PORT &&
+ need != ZFCP_ERP_ACTION_REOPEN_PORT_FORCED &&
+ need != ZFCP_ERP_ACTION_REOPEN_ADAPTER))
+ return NULL;
+
switch (need) {
case ZFCP_ERP_ACTION_REOPEN_LUN:
zfcp_sdev = sdev_to_zfcp(sdev);
--
2.20.1
next prev parent reply other threads:[~2019-08-05 13:07 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-05 13:02 [PATCH 4.14 00/53] 4.14.137-stable review Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 01/53] ARM: riscpc: fix DMA Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 02/53] ARM: dts: rockchip: Make rk3288-veyron-minnie run at hs200 Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 03/53] ARM: dts: rockchip: Make rk3288-veyron-mickeys emmc work again Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 04/53] ARM: dts: rockchip: Mark that the rk3288 timer might stop in suspend Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 05/53] ftrace: Enable trampoline when rec count returns back to one Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 06/53] kernel/module.c: Only return -EEXIST for modules that have finished loading Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 07/53] MIPS: lantiq: Fix bitfield masking Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 08/53] dmaengine: rcar-dmac: Reject zero-length slave DMA requests Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 09/53] clk: tegra210: fix PLLU and PLLU_OUT1 Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 10/53] fs/adfs: super: fix use-after-free bug Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 11/53] btrfs: fix minimum number of chunk errors for DUP Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 12/53] cifs: Fix a race condition with cifs_echo_request Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 13/53] ceph: fix improper use of smp_mb__before_atomic() Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 14/53] ceph: return -ERANGE if virtual xattr value didnt fit in buffer Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 15/53] ACPI: blacklist: fix clang warning for unused DMI table Greg Kroah-Hartman
2019-08-05 13:02 ` Greg Kroah-Hartman [this message]
2019-08-05 13:02 ` [PATCH 4.14 17/53] x86: kvm: avoid constant-conversion warning Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 18/53] ACPI: fix false-positive -Wuninitialized warning Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 19/53] be2net: Signal that the device cannot transmit during reconfiguration Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 20/53] x86/apic: Silence -Wtype-limits compiler warnings Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 21/53] x86: math-emu: Hide clang warnings for 16-bit overflow Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 22/53] mm/cma.c: fail if fixed declaration cant be honored Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 23/53] coda: add error handling for fget Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 24/53] coda: fix build using bare-metal toolchain Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 25/53] uapi linux/coda_psdev.h: move upc_req definition from uapi to kernel side headers Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 26/53] drivers/rapidio/devices/rio_mport_cdev.c: NUL terminate some strings Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 27/53] ipc/mqueue.c: only perform resource calculation if user valid Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 28/53] xen/pv: Fix a boot up hang revealed by int3 self test Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 29/53] x86/kvm: Dont call kvm_spurious_fault() from .fixup Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 30/53] x86/paravirt: Fix callee-saved function ELF sizes Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 31/53] x86, boot: Remove multiple copy of static function sanitize_boot_params() Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 32/53] drm/nouveau: fix memory leak in nouveau_conn_reset() Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 33/53] kbuild: initialize CLANG_FLAGS correctly in the top Makefile Greg Kroah-Hartman
2019-08-05 13:02 ` [PATCH 4.14 34/53] Btrfs: fix incremental send failure after deduplication Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 35/53] Btrfs: fix race leading to fs corruption after transaction abort Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 36/53] mmc: dw_mmc: Fix occasional hang after tuning on eMMC Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 37/53] gpiolib: fix incorrect IRQ requesting of an active-low lineevent Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 38/53] IB/hfi1: Fix Spectre v1 vulnerability Greg Kroah-Hartman
2019-08-05 14:16 ` Gustavo A. R. Silva
2019-08-26 9:06 ` Greg Kroah-Hartman
2019-08-26 21:23 ` Gustavo A. R. Silva
2019-08-05 13:03 ` [PATCH 4.14 39/53] selinux: fix memory leak in policydb_init() Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 40/53] s390/dasd: fix endless loop after read unit address configuration Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 41/53] parisc: Fix build of compressed kernel even with debug enabled Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 42/53] drivers/perf: arm_pmu: Fix failure path in PM notifier Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 43/53] nbd: replace kill_bdev() with __invalidate_device() again Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 44/53] xen/swiotlb: fix condition for calling xen_destroy_contiguous_region() Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 45/53] IB/mlx5: Fix unreg_umr to ignore the mkey state Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 46/53] IB/mlx5: Use direct mkey destroy command upon UMR unreg failure Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 47/53] IB/mlx5: Move MRs to a kernel PD when freeing them to the MR cache Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 48/53] IB/mlx5: Fix RSS Toeplitz setup to be aligned with the HW specification Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 49/53] IB/hfi1: Check for error on call to alloc_rsm_map_table Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 50/53] eeprom: at24: make spd world-readable again Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 51/53] objtool: Support GCC 9 cold subfunction naming scheme Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 52/53] gcc-9: properly declare the {pv,hv}clock_page storage Greg Kroah-Hartman
2019-08-05 13:03 ` [PATCH 4.14 53/53] x86/vdso: Prevent segfaults due to hoisted vclock reads Greg Kroah-Hartman
2019-08-06 1:06 ` [PATCH 4.14 00/53] 4.14.137-stable review shuah
2019-08-06 3:34 ` Naresh Kamboju
2019-08-06 7:16 ` Jack Wang
2019-08-06 15:49 ` Guenter Roeck
2019-08-06 18:29 ` Jon Hunter
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