I have not noticed any errors due to this, but the DMA configuration
looks racy. Setting the DMA mode bitfield in CAL_WR_DMA_CTRL supposedly
enables the DMA. However, the driver currently a) continues configuring
the DMA after setting the mode, and b) enables the DMA interrupts only
after setting the mode.
This probably doesn't cause any issues as there should be no data coming
in to the DMA yet, but it's still better to fix this.
Add a new function, cal_ctx_wr_dma_enable(), to set the DMA mode field,
and call that function only after the DMA config and the irq enabling
has been done.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
We already have functions to reserve and release a pix proc unit, but we
always reserve such and the code expects the pix proc unit to be used.
Add a new field, 'use_pix_proc', to indicate if the pix prox unit has
been reserved and should be used. Use the flag to skip programming pix
proc unit when not needed.
Note that we still always set the use_pix_proc flag to true.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
CAL has 4 pixel processing units but the units are not needed e.g. for
metadata. As we could be capturing 4 pixel streams and 4 metadata
streams, i.e. using 8 DMA contexts, we cannot assign a pixel processing
unit to every DMA context. Instead we need to reserve a pixel processing
unit only when needed.
Add functions to reserve and release a pix proc unit, and use them in
cal_ctx_prepare/unprepare. Note that for the time being we still always
reserve a pix proc unit.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Disable CSI2 context and pix proc in cal_ctx_stop() to ensure they are
not used if the same context is used later on a different PHY or without
pix proc.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Asserting ComplexIO reset seems to affect the HW (ie. asserting reset
will break an active capture), but the RESET_DONE bit never changes to
"reset is ongoing" state. Thus we always get a timeout.
Drop the wait, as it seems to achieve nothing.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
CAL driver currently ignores VC related errors. To help catch error
conditions, enable all the VC error interrupts and handle them in the
interrupt handler by printing an error.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The macros related to CAL_CSI2_VC_IRQ can be handled better by having
the VC number as a macro parameter.
Note that the macros are not used anywhere yet, so no other changes are
needed.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
CAL_HL_IRQ_MASK macro is used for both WDMA start and end status bits.
For clarity, rename CAL_HL_IRQ_MASK macro to CAL_HL_IRQ_WDMA_END_MASK
and CAL_HL_IRQ_WDMA_START_MASK.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Rename cal_ctx->index to dma_ctx to clarify that the field refers to the
DMA context number.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
CAL has 4 pixel processing contexts (PIX PROC) of which the driver
currently uses pix proc 0 for PHY0, and pix proc 1 for PHY1 (as the
driver supports only a single source per PHY).
Add a pix_proc field to cal_ctx to allow us to use different pix proc
contexts in the future
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
CAL has 8 CSI2 contexts per PHY, which are used to tag the incoming
data. The current driver only uses the first context, but we need to
support all of them to implement multi-stream support.
Add a csi2_ctx field to cal_ctx, which indicates which of the 8 CSI2
contexts is used for the particular cal_ctx. Also clean up the context
register macros to take the CSI2 context number as a parameter.
Note that before this patch the CSI2 context used for both PHYs was
always 0. This patch always uses cal_ctx index number as the CSI2
context. There is no functional difference, but this approach will work
also in the future when we use more than 1 CSI2 context per PHY.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
cal_ctx's index and cport fields are numbers less than 8. In the
following patches we will get a bunch of new fields, all of which are
similar small numbers, so lets change the type to u8.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
In the following patches we need to do context configuration which might
fail. Add new functions, cal_ctx_prepare and cal_ctx_unprepare, to
handle such configuration.
[hverkuil: fix spurious newline checkpatch warning]
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
CAL driver uses V4L2_CID_PIXEL_RATE to get the required pixel rate, and
then changes that value to link rate before configuring the registers.
Rewrite the code to use v4l2_get_link_freq(), which simplifies the code
as we get the link rate directly, and it also adds support for
V4L2_CID_LINK_FREQ.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
For some reason CAL_CTRL is written at the end of cal_ctx_wr_dma_config.
CAL_CTRL is a global (for CAL) register, so it should be independent of
contexts.
Move the code to cal_runtime_resume().
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
CAL driver uses "sensor" name to refer to the subdev connected to CAL.
As the subdev can also be a bridge, the naming is misleading and might
cause the reader to think it refers to the actual sensor at the end of
the pipeline.
Rename "sensor" to "source".
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
cal_camerarx->dev field is not used, remove it.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
v4l2-compliance complains about g/s_parm when using the non-MC API. Fix
it by adding the functions and just call v4l2_s/g_parm_cap for the
phy subdev.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The continue statement at the end of a for-loop has no effect,
remove it.
Addresses-Coverity: ("Continue has no effect")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Convert list_for_each() to list_for_each_entry() where
applicable.
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The max number of allowed logical addresses was set to 1 in
vivid, for no good reason. This prevented testing with multiple
logical addresses for the same CEC device. Increase this number to
CEC_MAX_LOG_ADDRS.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Without this patch, the TDA19971 chip's EDID is inactive.
EDID never worked with this driver, it was all tested with HDMI signal
sources which don't need EDID support.
Signed-off-by: Krzysztof Halasa <khalasa@piap.pl>
Fixes: 9ac0038db9 ("media: i2c: Add TDA1997x HDMI receiver driver")
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
deleted the repeated word 'the' in the comments.
Signed-off-by: lijian <lijian@yulong.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
SAMA5D2 does not have the YCYC field for the RLP (rounding, limiting,
packaging) module.
The YCYC field is supposed to work with interleaved YUV formats like YUYV.
In SAMA5D2, we have to use YYCC field, which is used for both planar
formats like YUV420 and interleaved formats like YUYV.
Fix the according rlp callback to replace the generic YCYC field (which
makes more sense from a logical point of view) with the required YYCC
field.
Fixes: debfa49687 ("media: atmel: atmel-isc-base: add support for more formats and additional pipeline modules")
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The variable ret is being initialized with a value that is never read,
it is being updated later on. The assignment is redundant and can be
removed.
Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Now that segment address is available, support for multi-slice frames
can be easily added.
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
If HEVC frame consists of multiple slices, segment address has to be
known in order to properly decode it.
Add segment address field to slice parameters.
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
As warned by smatch:
drivers/media/pci/ivtv/ivtv-i2c.c:245 ivtv_i2c_register() error: buffer overflow 'hw_devicenames' 21 <= 31
drivers/media/pci/ivtv/ivtv-i2c.c:266 ivtv_i2c_register() error: buffer overflow 'hw_addrs' 21 <= 31
drivers/media/pci/ivtv/ivtv-i2c.c:269 ivtv_i2c_register() error: buffer overflow 'hw_addrs' 21 <= 31
drivers/media/pci/ivtv/ivtv-i2c.c:275 ivtv_i2c_register() error: buffer overflow 'hw_addrs' 21 <= 31
drivers/media/pci/ivtv/ivtv-i2c.c:280 ivtv_i2c_register() error: buffer overflow 'hw_addrs' 21 <= 31
drivers/media/pci/ivtv/ivtv-i2c.c:290 ivtv_i2c_register() error: buffer overflow 'hw_addrs' 21 <= 31
The logic at ivtv_i2c_register() could let buffer overflows at
hw_devicenames and hw_addrs arrays.
This won't happen in practice due to a carefully-contructed
logic, but it is not error-prune.
Change the logic in a way that will make clearer that the
I2C hardware flags will affect the size of those two
arrays, and add an explicit check to avoid buffer overflows.
While here, use the bit macro.
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
As warned by smatch:
drivers/media/usb/uvc/uvc_v4l2.c:911 uvc_ioctl_g_input() error: doing dma on the stack (&i)
drivers/media/usb/uvc/uvc_v4l2.c:943 uvc_ioctl_s_input() error: doing dma on the stack (&i)
those two functions call uvc_query_ctrl passing a pointer to
a data at the DMA stack. those are used to send URBs via
usb_control_msg(). Using DMA stack is not supported and should
not work anymore on modern Linux versions.
So, use a kmalloc'ed buffer.
Cc: stable@vger.kernel.org # Kernel 4.9 and upper
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The logic at delta_ipc_open() tries to copy past the size of
the name passed to it:
drivers/media/platform/sti/delta/delta-ipc.c:178 delta_ipc_open() error: __memcpy() 'name' too small (17 vs 32)
Basically,this function is called just one with:
ret = delta_ipc_open(pctx, "JPEG_DECODER_HW0", ...);
The string used there has just 17 bytes. Yet, the logic tries
to copy the entire name size (32 bytes), which is plain wrong.
Replace it by strscpy, which is good enough to copy the string,
warranting that this will be NUL-terminated.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The logic at dib8000_get_init_prbs() has a few issues:
1. the tables used there has an extra unused value at the beginning;
2. the dprintk() message doesn't write the right value when
transmission mode is not 8K;
3. the array overflow validation is done by the callers.
Rewrite the code to fix such issues.
This should also shut up those smatch warnings:
drivers/media/dvb-frontends/dib8000.c:2125 dib8000_get_init_prbs() error: buffer overflow 'lut_prbs_8k' 14 <= 14
drivers/media/dvb-frontends/dib8000.c:2129 dib8000_get_init_prbs() error: buffer overflow 'lut_prbs_2k' 14 <= 14
drivers/media/dvb-frontends/dib8000.c:2131 dib8000_get_init_prbs() error: buffer overflow 'lut_prbs_4k' 14 <= 14
drivers/media/dvb-frontends/dib8000.c:2134 dib8000_get_init_prbs() error: buffer overflow 'lut_prbs_8k' 14 <= 14
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Drop the "default m", as options should default to disabled.
No other media driver is enabled by default.
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Fix typo in a define: CEC_OP_REC_SEQ_SATERDAY -> CEC_OP_REC_SEQ_SATURDAY
This isn't used yet in actual applications to the best of my knowledge,
and it certainly doesn't break the ABI since the value doesn't change.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Add Geniatech MyGica T230C2_LITE and T230A as many people
are asking support for these devices on forums.
Link: https://lore.kernel.org/linux-media/YMuptIYFLdwSmw//@kali
Signed-off-by: Ján Čáni <pego149@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
I know nothing about zone_device pages and !device_private pages; but if
try_to_migrate_one() will do nothing for them, then it's better that
try_to_migrate() filter them first, than trawl through all their vmas.
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Link: https://lore.kernel.org/lkml/1241d356-8ec9-f47b-a5ec-9b2bf66d242@google.com/
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In the unlikely race case that page_mlock_one() finds VM_LOCKED has been
cleared by the time it got page table lock, page_vma_mapped_walk_done()
must be called before returning, either explicitly, or by a final call
to page_vma_mapped_walk() - otherwise the page table remains locked.
Fixes: cd62734ca6 ("mm/rmap: split try_to_munlock from try_to_unmap")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/lkml/20210711151446.GB4070@xsang-OptiPlex-9020/
Link: https://lore.kernel.org/lkml/f71f8523-cba7-3342-40a7-114abc5d1f51@google.com/
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kernel recovers in due course from missing Mlocked pages: but there
was no point in calling page_mlock() (formerly known as
try_to_munlock()) on a THP, because nothing got done even when it was
found to be mapped in another VM_LOCKED vma.
It's true that we need to be careful: Mlocked accounting of pte-mapped
THPs is too difficult (so consistently avoided); but Mlocked accounting
of only-pmd-mapped THPs is supposed to work, even when multiple mappings
are mlocked and munlocked or munmapped. Refine the tests.
There is already a VM_BUG_ON_PAGE(PageDoubleMap) in page_mlock(), so
page_mlock_one() does not even have to worry about that complication.
(I said the kernel recovers: but would page reclaim be likely to split
THP before rediscovering that it's VM_LOCKED? I've not followed that up)
Fixes: 9a73f61bdb ("thp, mlock: do not mlock PTE-mapped file huge pages")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/lkml/cfa154c-d595-406-eb7d-eb9df730f944@google.com/
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Parallel developments in mm/rmap.c have left behind some out-of-date
comments: try_to_migrate_one() also accepts TTU_SYNC (already commented
in try_to_migrate() itself), and try_to_migrate() returns nothing at
all.
TTU_SPLIT_FREEZE has just been deleted, so reword the comment about it
in mm/huge_memory.c; and TTU_IGNORE_ACCESS was removed in 5.11, so
delete the "recently referenced" comment from try_to_unmap_one() (once
upon a time the comment was near the removed codeblock, but they drifted
apart).
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Link: https://lore.kernel.org/lkml/563ce5b2-7a44-5b4d-1dfd-59a0e65932a9@google.com/
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>