- 25 Jul, 2014 40 commits
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Stephen M. Cameron authored
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com> Reviewed-by: Joe Handzik <joseph.t.handzik@hp.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Vikas Chaudhary authored
Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com> Acked-by: Eddie Wai <eddie.wai@broadcom.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Saurav Kashyap authored
QLogic has acquired the NetXtremeII products and drivers from Broadcom. This patch re-brands bnx2fc driver as a QLogic driver Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com> Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com> Acked-by: Eddie Wai <eddie.wai@broadcom.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Vikas Chaudhary authored
QLogic has acquired the NetXtremeII products and drivers from Broadcom. This patch re-brands bnx2i driver as a QLogic driver Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com> Acked-by: Eddie Wai <eddie.wai@broadcom.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Martin K. Petersen authored
On systems with a non power-of-two CPU count the existing MSI-X grouping code failed to distribute interrupts correctly. Rework the code to handle arbitrary processor counts. Also remove the hardcoded upper limit on the number of processors so we can boot on large systems. Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Acked-by: Sreekanth Reddy <Sreekanth.reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Martin K. Petersen authored
On systems with a non power-of-two CPU count the existing MSI-X grouping code failed to distribute interrupts correctly. Rework the code to handle arbitrary processor counts. Also remove the hardcoded upper limit on the number of processors so we can boot on large systems. Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Acked-by: Sreekanth Reddy <Sreekanth.reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Lawrence authored
Fixes the following smatch warnings: drivers/message/fusion/mptbase.c:652 mptbase_reply() warn: variable dereferenced before check 'reply' (see line 639) [JL: No-brainer, the enclosing switch statement dereferences reply, so we can't get here unless reply is valid.] drivers/message/fusion/mptsas.c:1255 mptsas_taskmgmt_complete() error: we previously assumed 'pScsiTmReply' could be null (see line 1227) [HCH: Reading the code in mptsas_taskmgmt_complete it's pretty obvious that it can't do anything useful if mr/pScsiTmReply are NULL, so I suspect it would be best to just return at the beginning of the function. I'd love to understand if it actually could ever be zero, which I doubt. Maybe the LSI people can shed some light on that?] drivers/message/fusion/mptsas.c:3888 mptsas_not_responding_devices() error: we previously assumed 'port_info->phy_info' could be null (see line 3875) [HCH: It's pretty obvious from reading mptsas_sas_io_unit_pg0 that we never register a port_info with a NULL phy_info in the lists, so all NULL checks on it could be deleted.] drivers/message/fusion/mptscsih.c:1284 mptscsih_info() error: we previously assumed 'h' could be null (see line 1274) [HCH: shost_priv can't return NULL, so the if (h) should be removed.] drivers/message/fusion/mptscsih.c:1388 mptscsih_qcmd() error: we previously assumed 'vdevice' could be null (see line 1373) [HCH: vdevice can't ever be NULL here, it's allocated in ->slave_alloc and thus guaranteed to be around when ->queuecommand is called.] Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Lawrence authored
Tack the firmware reply event_data payload to the end of its corresponding struct fw_event_work allocation. Rework fw_event_work allocation calculations to include the event_data size where appropriate. This clarifies the code a bit and avoids the following smatch warnings: drivers/message/fusion/mptsas.c:1003 mptsas_queue_device_delete() error: memcpy() 'fw_event->event_data' too small (29 vs 36) drivers/message/fusion/mptsas.c:1017 mptsas_queue_rescan() error: not allocating enough data 168 vs 160 Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Lawrence authored
The struct _MPT_ADAPTER doesn't need a full copy of the product string, so prod_name can point to the string literal storage that the driver already provides. Avoids the following smatch warning: drivers/message/fusion/mptbase.c:2858 MptDisplayIocCapabilities() warn: this array is probably non-NULL. 'ioc->prod_name' Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Lawrence authored
Let memdup_user handle the kmalloc, copy_from_user and error checking kfree code. Spotted by the following smatch (false positive) warning: drivers/message/fusion/mptctl.c:1369 mptctl_getiocinfo() warn: possible info leak 'karg' Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Lawrence authored
Fixes the following smatch warnings: drivers/message/fusion/mptfc.c:529 mptfc_target_destroy() info: redundant null check on starget->hostdata calling kfree() drivers/message/fusion/mptspi.c:465 mptspi_target_destroy() info: redundant null check on starget->hostdata calling kfree() Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Lawrence authored
Fixes the following sparse warnings: drivers/message/fusion/mptbase.c:7011:1: warning: symbol 'mpt_SoftResetHandler' was not declared. Should it be static? drivers/message/fusion/mptsas.c:1578:23: warning: symbol 'mptsas_refreshing_device_handles' was not declared. Should it be static? drivers/message/fusion/mptsas.c:3653:24: warning: symbol 'mptsas_expander_add' was not declared. Should it be static? drivers/message/fusion/mptsas.c:5327:1: warning: symbol 'mptsas_shutdown' was not declared. Should it be static? drivers/message/fusion/mptspi.c:624:1: warning: symbol 'mptscsih_quiesce_raid' was not declared. Should it be static? Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Lawrence authored
Tack the firmware reply event_data payload to the end of its corresponding struct fw_event_work allocation. This matches the convention in the mptfusion driver and simplifies the code. This avoids the following smatch warning: drivers/scsi/mpt3sas/mpt3sas_scsih.c:2519 mpt3sas_send_trigger_data_event() warn: possible memory leak of 'fw_event' Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Lawrence authored
In _scsih_{slave,target}_alloc, an incorrect structure type is passed to sizeof() when allocating storage for hostdata. Luckily larger structure types were used, so at least the wrong sizes were safe: struct scsi_device (1784 bytes) > struct MPT3SAS_DEVICE (24 bytes) struct scsi_target (760 bytes) > struct MPT3SAS_TARGET (32 bytes) This fixes the following smatch warnings: drivers/scsi/mpt3sas/mpt3sas_scsih.c:1166 _scsih_target_alloc() warn: struct type mismatch 'MPT3SAS_TARGET vs scsi_target' drivers/scsi/mpt3sas/mpt3sas_scsih.c:1280 _scsih_slave_alloc() warn: struct type mismatch 'MPT3SAS_DEVICE vs scsi_device' Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Lawrence authored
The MPT2SAS_ADAPTER reply_post_host_index[] holds calculated addresses in memory mapped register space. Add an "__iomem" annotation to silence the following sparse warnings: drivers/scsi/mpt2sas/mpt2sas_base.c:1006:43: warning: incorrect type in argument 2 (different address spaces) expected void volatile [noderef] <asn:2>*addr got unsigned long long [usertype] *<noident> drivers/scsi/mpt2sas/mpt2sas_base.c:4299:22: warning: cast removes address space of expression drivers/scsi/mpt2sas/mpt2sas_base.c:4303:27: warning: cast removes address space of expression Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Lawrence authored
Tack the firmware reply event_data payload to the end of its corresponding struct fw_event_work allocation. This matches the convention in the mptfusion driver and simplifies the code. Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Lawrence authored
In _scsih_{slave,target}_alloc, an incorrect structure type is passed to sizeof() when allocating storage for hostdata. Luckily larger structure types were used, so at least the wrong sizes were safe: struct scsi_device (1784 bytes) > struct MPT2SAS_DEVICE (24 bytes) struct scsi_target (760 bytes) > struct MPT2SAS_TARGET (40 bytes) This fixes the following smatch warnings: drivers/scsi/mpt2sas/mpt2sas_scsih.c:1295 _scsih_target_alloc() warn: struct type mismatch 'MPT2SAS_TARGET vs scsi_target' drivers/scsi/mpt2sas/mpt2sas_scsih.c:1409 _scsih_slave_alloc() warn: struct type mismatch 'MPT2SAS_DEVICE vs scsi_device' Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Arnd Bergmann authored
Building an allmodconfig ARM kernel, I get multiple such warnings because of a spinlock contained in packed structure in the 3w-xxxx driver: ../drivers/scsi/3w-xxxx.c: In function 'tw_chrdev_ioctl': ../drivers/scsi/3w-xxxx.c:1001:68: warning: mis-aligned access used for structure member [-fstrict-volatile-bitfields] timeout = wait_event_timeout(tw_dev->ioctl_wqueue, tw_dev->chrdev_request_id == TW_IOCTL_CHRDEV_FREE, timeout); ^ ../drivers/scsi/3w-xxxx.c:1001:68: note: when a volatile object spans multiple type-sized locations, the compiler must choose between using a single mis-aligned access to preserve the volatility, or using multiple aligned accesses to avoid runtime faults; this code may fail at runtime if the hardware does not allow this access The same bug apparently was present in 3w-sas and 3w-9xxx, but has been fixed in the past. This patch uses the same fix by moving the pragma in front of the TW_Device_Extension definition, so it only covers hardware structures. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Adam Radford <aradford@gmail.com> Cc: Adam Radford <linuxraid@lsi.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Arnd Bergmann authored
The NCR53c406a scsi driver normally does not use DMA, unless the USE_PIO macro is disabled by modifying the source code. The call to free_dma() for some reason uses #ifdef USE_DMA, which does not do the right thing, since USE_DMA is defined as a boolean that is either 0 or 1, but always present. One case where it gets in the way is randconfig builds on ARM, which depending on the configuration does not provide a free_dma() function, causing this build error: drivers/scsi/NCR53c406a.c: In function 'NCR53c406a_release': drivers/scsi/NCR53c406a.c:600:3: error: implicit declaration of function 'free_dma' [-Werror=implicit-function-declaration] free_dma(shost->dma_channel); ^ This changes the code to use #if USE_DMA, to match the rest of the file, which seems to be what the author intended. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Arnd Bergmann authored
The qlogicfas scsi driver does not use DMA, and the call to free_dma() in its exit function seems to have been copied incorrectly from another driver but never caused trouble. One case where it gets in the way is randconfig builds on ARM, which depending on the configuration does not provide a free_dma() function, causing this build error: drivers/scsi/qlogicfas.c: In function 'qlogicfas_release': drivers/scsi/qlogicfas.c:175:3: error: implicit declaration of function 'free_dma' [-Werror=implicit-function-declaration] free_dma(shost->dma_channel); ^ Removing the incorrect function calls should be the obvious fix for this, with no downsides. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Arnd Bergmann authored
The pas16 scsi driver does not use DMA, and the call to free_dma() in its exit function seems to have been copied incorrectly from another driver but never caused trouble. One case where it gets in the way is randconfig builds on ARM, which depending on the configuration does not provide a free_dma() function, causing this build error: drivers/scsi/pas16.c: In function 'pas16_release': drivers/scsi/pas16.c:611:3: error: implicit declaration of function 'free_dma' [-Werror=implicit-function-declaration] free_dma(shost->dma_channel); Removing the incorrect function calls should be the obvious fix for this, with no downsides. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Arnd Bergmann authored
The advansys SCSI driver uses the dma_cache_sync function, which is not available on the ARM architecture, and cannot be implemented correctly, so we always get this build error: drivers/scsi/advansys.c: In function 'advansys_get_sense_buffer_dma': drivers/scsi/advansys.c:7882:2: error: implicit declaration of function 'dma_cache_sync' [-Werror=implicit-function-declaration] dma_cache_sync(board->dev, scp->sense_buffer, ^ It seems nobody has missed this driver so far, so let's just disable it for ARM to help randconfig builds. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Tyrel Datwyler authored
Added big endian annotations to relevant data structure fields, and necessary byte swappings to support little endian builds. Signed-off-by: Brian King <brking@linux.vnet.ibm.com> Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Perches authored
Use the zeroing function instead of dma_alloc_coherent & memset(,0,) Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Saurav Kashyap <saurav.kashyap@qlogic.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Fabian Frederick authored
Use macro definition Signed-off-by: Fabian Frederick <fabf@skynet.be> Acked-by: Anil Gurumurthy <anil.gurumurthy@qlogic.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Peter Senna Tschudin authored
This patch remove variables that are initialized with a constant, are never updated, and are only used as parameter of return. Return the constant instead of using a variable. Verified by compilation only. The coccinelle script that find and fixes this issue is: // <smpl> @@ type T; constant C; identifier ret; @@ - T ret = C; ... when != ret when strict return - ret + C ; // </smpl> Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com> Acked-by: Sudarsana Kalluru <Sudarsana.Kalluru@qlogic.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Ben Hutchings authored
bfa_swap_words() shifts its argument (assumed to be 64-bit) by 32 bits each way. In two places the argument type is dma_addr_t, which may be 32-bit, in which case the effect of the bit shift is undefined: drivers/scsi/bfa/bfa_fcpim.c: In function 'bfa_ioim_send_ioreq': drivers/scsi/bfa/bfa_fcpim.c:2497:4: warning: left shift count >= width of type [enabled by default] addr = bfa_sgaddr_le(sg_dma_address(sg)); ^ drivers/scsi/bfa/bfa_fcpim.c:2497:4: warning: right shift count >= width of type [enabled by default] drivers/scsi/bfa/bfa_fcpim.c:2509:4: warning: left shift count >= width of type [enabled by default] addr = bfa_sgaddr_le(sg_dma_address(sg)); ^ drivers/scsi/bfa/bfa_fcpim.c:2509:4: warning: right shift count >= width of type [enabled by default] Avoid this by adding casts to u64 in bfa_swap_words(). Compile-tested only. Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Acked-by: Anil Gurumurthy <anil.gurumurthy@qlogic.com> Cc: stable@vger.kernel.org Fixes: f16a1750 ('[SCSI] bfa: remove all OS wrappers') Signed-off-by: Christoph Hellwig <hch@lst.de>
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Joe Perches authored
Use the zeroing function instead of dma_alloc_coherent & memset(,0,) Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Anil Gurumurthy <anil.gurumurthy@qlogic.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Himangi Saraogi authored
Use kstrdup when the goal of an allocation is copy a string into the allocated region. The Coccinelle semantic patch that makes this change is as follows: // <smpl> @@ expression from,to; expression flag,E1,E2; statement S; @@ - to = kmalloc(strlen(from) + 1,flag); + to = kstrdup(from, flag); ... when != \(from = E1 \| to = E1 \) if (to==NULL || ...) S ... when != \(from = E2 \| to = E2 \) - strcpy(to, from); // </smpl> Signed-off-by: Himangi Saraogi <himangi774@gmail.com> Acked-by: Julia Lawall <julia.lawall@lip6.fr> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Dick Kennedy authored
These speeds are to support the next generation of FCoE port speeds. Signed-off-by: Dick Kennedy <Dick.Kennedy@Emulex.Com> Reviewed-by: Ewan D. Milne <emilne@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Mike Christie authored
The custom stats is an array with custom_length indicating the length of the array. This patch fixes bnx2i and be2iscsi's setting of the custom stats length. They both just have the one, eh_abort_cnt, so that should be in the first entry of the custom array and custom_length should then be one. Reported-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se> Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Acked-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com> Acked-by: Eddie Wai <eddie.wai@broadcom.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Nick Black' via open-iscsi authored
Remove two redundant casts from char * to char *. Signed-off-by: Nick Black <nlb@google.com> Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Paul Bolle authored
The Kconfig symbols SCSI_TGT and SCSI_FC_TGT_ATTRS are unused since "tgt: removal". Setting them has no effect. Remove these symbols. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Christoph Hellwig <hch@lst.de>
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K. Y. Srinivasan authored
Commit ID: 7e660100 added code to derive the FLUSH_TIMEOUT from the basic I/O timeout. However, this patch did not use the basic I/O timeout of the device. Fix this bug. Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Reviewed-by: James Bottomley <JBottomley@Parallels.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Martin K. Petersen authored
Despite supporting modern SCSI features some storage devices continue to claim conformance to an older version of the SPC spec. This is done for compatibility with legacy operating systems. Linux by default will not attempt to read VPD pages on devices that claim SPC-2 or older. Introduce a blacklist flag that can be used to trigger VPD page inquiries on devices that are known to support them. Reported-by: KY Srinivasan <kys@microsoft.com> Tested-by: KY Srinivasan <kys@microsoft.com> Reviewed-by: KY Srinivasan <kys@microsoft.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> CC: <stable@vger.kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Christoph Hellwig authored
We currently set the field in common code based on the device type, but then only use it in the cdrom driver which also overrides the value previously set in the generic code. Just leave this entirely to the CDROM driver to make everyones life simpler. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
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Christoph Hellwig authored
Make sure we have a symbolic name for the ZBC type available, so that e.g. patch for a SATA to translate ZAC commands can make use of it. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
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Christoph Hellwig authored
Add two new device types, most importantly the zoned block device one. Split from an earlier patch by Hannes Reinecke. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
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Christoph Hellwig authored
Current the midlayer fakes up a struct request for the explicit reset ioctls, and those don't have a tag allocated to them. The fnic driver pokes into midlayer structures to paper over this design issue, but that won't work for the blk-mq case. Either someone who can actually test the hardware will have to come up with a similar hack for the blk-mq case, or we'll have to bite the bullet and fix the way the EH ioctls work for real, but until that happens we fail these explicit requests here. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com> Cc: Hiral Patel <hiralpat@cisco.com> Cc: Suma Ramars <sramars@cisco.com> Cc: Brian Uchino <buchino@cisco.com>
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Christoph Hellwig authored
This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
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