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udev-cache fixes

PATCH New Richard Tollerton 1 participant 10 messages Dec 11, 2014

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Richard Tollerton

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#0 lore raw

v3 cover udev-cache fixes

This is v3 of the udev-cache changes previously submitted by Ben Shelton and myself last summer. This is primarily a cleanup of the patches that didn't make it into dizzy; the only significant behavioral difference is that I'm now making use of udevadm control --stop-exec-queue and udevadm control --start-exec-queue to completely close the race condition between sysconf generation and udev-cache tarball generation.

The following changes since commit 219e793907406eabf632e784e3a11ab9acb77cfb:

qemu/libc-package: Fix qemu option handling (2014-12-05 17:59:42 +0000)

are available in the git repository at:

git://github.com/rtollert/openembedded-core dev/rtollert/udev-cache-9
https://github.com/rtollert/openembedded-core/tree/dev/rtollert/udev-cache-9

Richard Tollerton (9):
udev-cache: stop race between sysconf and cache generation
udev-cache: replace readfiles() with cmp
udev-cache: don't generate sysconf twice
udev-cache: refactor sysconf generation
udev-cache: Clean up message when cache is invalidated
udev-cache: always warn on console if invalidated
udev-cache: invalidate on rules.d changes
udev-cache: Update cache asynchronously
udev-cache: refactor conditionals and error handling

 meta/recipes-core/udev/udev/init       | 56 ++++++++++++++++++----------------
 meta/recipes-core/udev/udev/udev-cache | 37 ++++++++++++++++++++--
 2 files changed, 63 insertions(+), 30 deletions(-)
Signature · 1 line
2.1.3
author
#1 lore raw

PATCH v3 1/9 udev-cache: stop race between sysconf and cache generation

The validity of the udev cache is determined by the sysconf file (/etc/udev/cache.data). Currently, there is a substantial delay between sysconf generation in /etc/init.d/udev and cache generation in /etc/init.d/udev-cache. If a hotplug event arrives in the middle of this, then the sysconf will be out of date with respect to the cache.

The solution is two-pronged. First, we minimize the race window by regenerating the sysconf immediately before the cache, in /etc/init.d/udev-cache. This allows us to kill the race entirely by stopping the udev event queue while the sysconf and cache are being generated.

Signed-off-by Richard Tollerton <[email protected]>
---
 meta/recipes-core/udev/udev/udev-cache | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
meta/recipes-core/udev/udev/udev-cache +18 -0
index 497d257..a1410f5 100644
@@ -19,8 +19,22 @@ export TZ=/etc/localtime
 DEVCACHE_TMP="/dev/shm/udev-cache-tmp.tar"
 SYSCONF_CACHED="/etc/udev/cache.data"
 SYSCONF_TMP="/dev/shm/udev.cache"
+
+# A list of files which are used as a criteria to judge whether the udev cache could be reused.
+CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices /proc/atags"
 [ -f /etc/default/udev-cache ] && . /etc/default/udev-cache
 
+readfiles () {
+   READDATA=""
+   for filename in $@; do
+	   if [ -r $filename ]; then
+		   while read line; do
+			   READDATA="$READDATA$line"
+		   done < $filename
+	   fi
+   done
+}
+
 if [ "$ROOTFS_READ_ONLY" = "yes" ]; then
     [ "$VERBOSE" != "no" ] && echo "udev-cache: read-only rootfs, skip generating udev-cache"
     exit 0

@@ -28,11 +42,15 @@ fi
 
 if [ "$DEVCACHE" != "" -a -e "$SYSCONF_TMP" ]; then
 	echo "Populating dev cache"
+	udevadm control --stop-exec-queue
+	readfiles $CMP_FILE_LIST
+	echo "$READDATA" > "$SYSCONF_TMP"
 	find /dev -xdev \( -type b -o -type c -o -type l \) | cut -c 2- \
 		| xargs tar cf "${DEVCACHE_TMP}" -T-
 	gzip < "${DEVCACHE_TMP}" > "$DEVCACHE"
 	rm -f "${DEVCACHE_TMP}"
 	mv "$SYSCONF_TMP" "$SYSCONF_CACHED"
+	udevadm control --start-exec-queue
 fi
 
 exit 0
Signature · 1 line
2.1.3
author
#2 lore raw

PATCH v3 2/9 udev-cache: replace readfiles() with cmp

In reply to Richard Tollerton

Currently, udev-cache system configurations are compared as shell string variables, read into memory with the readfiles() function. This is more complex, and significantly (27-41%) slower, than comparing them using cmp. (Performance was verified on both Cortex-A9 and Intel Nehalem systems.)

So just use cmp. This requires a few other small changes:

exclude /proc/atags from CMP_FILE_LIST if it doesn't exist to avoid errors in cat and cmp.

cmp -q doesn't exist in busybox, so instead, redirect output to /dev/null.

Signed-off-by Richard Tollerton <[email protected]>
---
 meta/recipes-core/udev/udev/init       | 29 +++++++----------------------
 meta/recipes-core/udev/udev/udev-cache | 17 +++--------------
 2 files changed, 10 insertions(+), 36 deletions(-)
meta/recipes-core/udev/udev/init +7 -22
index d26cbfc..ee79670 100644
@@ -20,17 +20,6 @@ SYSCONF_TMP="/dev/shm/udev.cache"
 [ -f /etc/udev/udev.conf ] && . /etc/udev/udev.conf
 [ -f /etc/default/rcS ] && . /etc/default/rcS
 
-readfiles () {
-   READDATA=""
-   for filename in $@; do
-	   if [ -r $filename ]; then
-		   while read line; do
-			   READDATA="$READDATA$line"
-		   done < $filename
-	   fi
-   done
-}
-
 kill_udevd () {
     pid=`pidof -x udevd`
     [ -n "$pid" ] && kill $pid

@@ -63,14 +52,12 @@ case "$1" in
 
     # Cache handling.
     # A list of files which are used as a criteria to judge whether the udev cache could be reused.
-    CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices /proc/atags"
+    CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices"
+    [ -f /proc/atags ] && CMP_FILE_LIST="$CMP_FILE_LIST /proc/atags"
     if [ "$DEVCACHE" != "" ]; then
             if [ -e $DEVCACHE ]; then
-		    readfiles $CMP_FILE_LIST
-		    NEWDATA="$READDATA"
-		    readfiles "$SYSCONF_CACHED"
-		    OLDDATA="$READDATA"
-		    if [ "$OLDDATA" = "$NEWDATA" ]; then
+		    cat -- "$CMP_FILE_LIST" > "$SYSCONF_TMP"
+		    if cmp $SYSCONF_CACHED $SYSCONF_TMP >/dev/null; then
                             tar xmf $DEVCACHE -C / -m
                             not_first_boot=1
                             [ "$VERBOSE" != "no" ] && echo "udev: using cache file $DEVCACHE"

@@ -80,17 +67,15 @@ case "$1" in
 			    if [ "$VERBOSE" != "no" ]; then
 				    echo "udev: udev cache not used"
 				    echo "udev: we use $CMP_FILE_LIST as criteria to judge whether the cache /dev could be resued"
-				    echo "udev: olddata: $OLDDATA"
-				    echo "udev: newdata: $NEWDATA"
+				    echo "udev: cached sysconf:  $SYSCONF_CACHED"
+				    echo "udev: current sysconf: $SYSCONF_TMP"
 			    fi
-			    echo "$NEWDATA" > "$SYSCONF_TMP"
                     fi
 	    else
 		    if [ "$ROOTFS_READ_ONLY" != "yes" ]; then
 			    # If rootfs is not read-only, it's possible that a new udev cache would be generated;
 			    # otherwise, we do not bother to read files.
-			    readfiles $CMP_FILE_LIST
-			    echo "$READDATA" > "$SYSCONF_TMP"
+			    cat -- "$CMP_FILE_LIST" > "$SYSCONF_TMP"
 		    fi
             fi
     fi
meta/recipes-core/udev/udev/udev-cache +3 -14
index a1410f5..e0e1c39 100644
@@ -21,20 +21,10 @@ SYSCONF_CACHED="/etc/udev/cache.data"
 SYSCONF_TMP="/dev/shm/udev.cache"
 
 # A list of files which are used as a criteria to judge whether the udev cache could be reused.
-CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices /proc/atags"
+CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices"
+[ -f /proc/atags ] && CMP_FILE_LIST="$CMP_FILE_LIST /proc/atags"
 [ -f /etc/default/udev-cache ] && . /etc/default/udev-cache
 
-readfiles () {
-   READDATA=""
-   for filename in $@; do
-	   if [ -r $filename ]; then
-		   while read line; do
-			   READDATA="$READDATA$line"
-		   done < $filename
-	   fi
-   done
-}
-
 if [ "$ROOTFS_READ_ONLY" = "yes" ]; then
     [ "$VERBOSE" != "no" ] && echo "udev-cache: read-only rootfs, skip generating udev-cache"
     exit 0

@@ -43,8 +33,7 @@ fi
 if [ "$DEVCACHE" != "" -a -e "$SYSCONF_TMP" ]; then
 	echo "Populating dev cache"
 	udevadm control --stop-exec-queue
-	readfiles $CMP_FILE_LIST
-	echo "$READDATA" > "$SYSCONF_TMP"
+        cat -- $CMP_FILE_LIST > "$SYSCONF_TMP"
 	find /dev -xdev \( -type b -o -type c -o -type l \) | cut -c 2- \
 		| xargs tar cf "${DEVCACHE_TMP}" -T-
 	gzip < "${DEVCACHE_TMP}" > "$DEVCACHE"
Signature · 1 line
2.1.3
author
#3 lore raw

PATCH v3 3/9 udev-cache: don't generate sysconf twice

In reply to Richard Tollerton

The udev initscript signals udev-cache to run by generating a new sysconf; but udev-cache now overwrites that with its own copy. To eliminate the needless sysconf generating in udev, we instead trigger udev-cache to run by touching a new file $DEVCACHE_REGEN.

Signed-off-by Richard Tollerton <[email protected]>
---
 meta/recipes-core/udev/udev/init       | 5 ++++-
 meta/recipes-core/udev/udev/udev-cache | 4 +++-
 2 files changed, 7 insertions(+), 2 deletions(-)
meta/recipes-core/udev/udev/init +4 -1
index ee79670..337b6d4 100644
@@ -16,6 +16,7 @@ export TZ=/etc/localtime
 [ -x @UDEVD@ ] || exit 1
 SYSCONF_CACHED="/etc/udev/cache.data"
 SYSCONF_TMP="/dev/shm/udev.cache"
+DEVCACHE_REGEN="/dev/shm/udev-regen" # create to request cache regen
 [ -f /etc/default/udev-cache ] && . /etc/default/udev-cache
 [ -f /etc/udev/udev.conf ] && . /etc/udev/udev.conf
 [ -f /etc/default/rcS ] && . /etc/default/rcS

@@ -62,6 +63,7 @@ case "$1" in
                             not_first_boot=1
                             [ "$VERBOSE" != "no" ] && echo "udev: using cache file $DEVCACHE"
                             [ -e $SYSCONF_TMP ] && rm -f "$SYSCONF_TMP"
+                            [ -e "$DEVCACHE_REGEN" ] && rm -f "$DEVCACHE_REGEN"
                     else
 			    # Output detailed reason why the cached /dev is not used
 			    if [ "$VERBOSE" != "no" ]; then

@@ -70,12 +72,13 @@ case "$1" in
 				    echo "udev: cached sysconf:  $SYSCONF_CACHED"
 				    echo "udev: current sysconf: $SYSCONF_TMP"
 			    fi
+			    touch "$DEVCACHE_REGEN"
                     fi
 	    else
 		    if [ "$ROOTFS_READ_ONLY" != "yes" ]; then
 			    # If rootfs is not read-only, it's possible that a new udev cache would be generated;
 			    # otherwise, we do not bother to read files.
-			    cat -- "$CMP_FILE_LIST" > "$SYSCONF_TMP"
+			    touch "$DEVCACHE_REGEN"
 		    fi
             fi
     fi
meta/recipes-core/udev/udev/udev-cache +3 -1
index e0e1c39..814ef54 100644
@@ -19,6 +19,7 @@ export TZ=/etc/localtime
 DEVCACHE_TMP="/dev/shm/udev-cache-tmp.tar"
 SYSCONF_CACHED="/etc/udev/cache.data"
 SYSCONF_TMP="/dev/shm/udev.cache"
+DEVCACHE_REGEN="/dev/shm/udev-regen" # create to request cache regen
 
 # A list of files which are used as a criteria to judge whether the udev cache could be reused.
 CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices"

@@ -30,7 +31,7 @@ if [ "$ROOTFS_READ_ONLY" = "yes" ]; then
     exit 0
 fi
 
-if [ "$DEVCACHE" != "" -a -e "$SYSCONF_TMP" ]; then
+if [ "$DEVCACHE" != "" -a -e "$DEVCACHE_REGEN" ]; then
 	echo "Populating dev cache"
 	udevadm control --stop-exec-queue
         cat -- $CMP_FILE_LIST > "$SYSCONF_TMP"

@@ -40,6 +41,7 @@ if [ "$DEVCACHE" != "" -a -e "$SYSCONF_TMP" ]; then
 	rm -f "${DEVCACHE_TMP}"
 	mv "$SYSCONF_TMP" "$SYSCONF_CACHED"
 	udevadm control --start-exec-queue
+	rm -f "$DEVCACHE_REGEN"
 fi
 
 exit 0
Signature · 1 line
2.1.3
author
#4 lore raw

PATCH v3 4/9 udev-cache: refactor sysconf generation

In reply to Richard Tollerton

The current system configuration needs to be generated both inside udev (to compare against the cached system configuration) and udev-cache (to regenerate the cached system configuration). Use a single function definition for this task, duplicated across both initscripts. This also allows administrators to modify it for machine-specific requirements.

Signed-off-by Richard Tollerton <[email protected]>
---
 meta/recipes-core/udev/udev/init       | 15 +++++++++++----
 meta/recipes-core/udev/udev/udev-cache |  8 +++++++-
 2 files changed, 18 insertions(+), 5 deletions(-)
meta/recipes-core/udev/udev/init +11 -4
index 337b6d4..96578bc 100644
@@ -17,6 +17,16 @@ export TZ=/etc/localtime
 SYSCONF_CACHED="/etc/udev/cache.data"
 SYSCONF_TMP="/dev/shm/udev.cache"
 DEVCACHE_REGEN="/dev/shm/udev-regen" # create to request cache regen
+
+# A list of files which are used as a criteria to judge whether the udev cache could be reused.
+CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices"
+[ -f /proc/atags ] && CMP_FILE_LIST="$CMP_FILE_LIST /proc/atags"
+
+# Command to compute system configuration.
+sysconf_cmd () {
+	cat -- $CMP_FILE_LIST
+}
+
 [ -f /etc/default/udev-cache ] && . /etc/default/udev-cache
 [ -f /etc/udev/udev.conf ] && . /etc/udev/udev.conf
 [ -f /etc/default/rcS ] && . /etc/default/rcS

@@ -52,12 +62,9 @@ case "$1" in
     mkdir -m 1777 -p /var/volatile/tmp
 
     # Cache handling.
-    # A list of files which are used as a criteria to judge whether the udev cache could be reused.
-    CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices"
-    [ -f /proc/atags ] && CMP_FILE_LIST="$CMP_FILE_LIST /proc/atags"
     if [ "$DEVCACHE" != "" ]; then
             if [ -e $DEVCACHE ]; then
-		    cat -- "$CMP_FILE_LIST" > "$SYSCONF_TMP"
+		    sysconf_cmd > "$SYSCONF_TMP"
 		    if cmp $SYSCONF_CACHED $SYSCONF_TMP >/dev/null; then
                             tar xmf $DEVCACHE -C / -m
                             not_first_boot=1
meta/recipes-core/udev/udev/udev-cache +7 -1
index 814ef54..4d50876 100644
@@ -24,6 +24,12 @@ DEVCACHE_REGEN="/dev/shm/udev-regen" # create to request cache regen
 # A list of files which are used as a criteria to judge whether the udev cache could be reused.
 CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices"
 [ -f /proc/atags ] && CMP_FILE_LIST="$CMP_FILE_LIST /proc/atags"
+
+# Command to compute system configuration.
+sysconf_cmd () {
+	cat -- $CMP_FILE_LIST
+}
+
 [ -f /etc/default/udev-cache ] && . /etc/default/udev-cache
 
 if [ "$ROOTFS_READ_ONLY" = "yes" ]; then

@@ -34,7 +40,7 @@ fi
 if [ "$DEVCACHE" != "" -a -e "$DEVCACHE_REGEN" ]; then
 	echo "Populating dev cache"
 	udevadm control --stop-exec-queue
-        cat -- $CMP_FILE_LIST > "$SYSCONF_TMP"
+        sysconf_cmd > "$SYSCONF_TMP"
 	find /dev -xdev \( -type b -o -type c -o -type l \) | cut -c 2- \
 		| xargs tar cf "${DEVCACHE_TMP}" -T-
 	gzip < "${DEVCACHE_TMP}" > "$DEVCACHE"
Signature · 1 line
2.1.3
author
#5 lore raw

PATCH v3 5/9 udev-cache: Clean up message when cache is invalidated

In reply to Richard Tollerton

Replace a bunch of echo's with a single cat<<EOF. Take this opportunity to more clearly communicate what is going on with the cache and what files are being looked at.

Signed-off-by Richard Tollerton <[email protected]>
---
 meta/recipes-core/udev/udev/init | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
meta/recipes-core/udev/udev/init +7 -4
index 96578bc..9a8b09d 100644
@@ -74,10 +74,13 @@ case "$1" in
                     else
 			    # Output detailed reason why the cached /dev is not used
 			    if [ "$VERBOSE" != "no" ]; then
-				    echo "udev: udev cache not used"
-				    echo "udev: we use $CMP_FILE_LIST as criteria to judge whether the cache /dev could be resued"
-				    echo "udev: cached sysconf:  $SYSCONF_CACHED"
-				    echo "udev: current sysconf: $SYSCONF_TMP"
+				    cat <<EOF
+udev: Not using udev cache because of changes detected in the following files:
+udev:     $CMP_FILE_LIST
+udev: The udev cache will be regenerated. To identify the detected changes,
+udev: compare the cached sysconf at   $SYSCONF_CACHED
+udev: against the current sysconf at  $SYSCONF_TMP
+EOF
 			    fi
 			    touch "$DEVCACHE_REGEN"
                     fi
Signature · 1 line
2.1.3
author
#6 lore raw

PATCH v3 6/9 udev-cache: always warn on console if invalidated

In reply to Richard Tollerton

Failure to use the udev cache is a significant enough impact to the boot time (possibly seconds) that it should always be reported on the console, regardless of the VERBOSE setting.

Signed-off-by Richard Tollerton <[email protected]>
---
 meta/recipes-core/udev/udev/init | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
meta/recipes-core/udev/udev/init +1 -3
index 9a8b09d..32c677a 100644
@@ -73,15 +73,13 @@ case "$1" in
                             [ -e "$DEVCACHE_REGEN" ] && rm -f "$DEVCACHE_REGEN"
                     else
 			    # Output detailed reason why the cached /dev is not used
-			    if [ "$VERBOSE" != "no" ]; then
-				    cat <<EOF
+			    cat <<EOF
 udev: Not using udev cache because of changes detected in the following files:
 udev:     $CMP_FILE_LIST
 udev: The udev cache will be regenerated. To identify the detected changes,
 udev: compare the cached sysconf at   $SYSCONF_CACHED
 udev: against the current sysconf at  $SYSCONF_TMP
 EOF
-			    fi
 			    touch "$DEVCACHE_REGEN"
                     fi
 	    else
Signature · 1 line
2.1.3
author
#7 lore raw

PATCH v3 7/9 udev-cache: invalidate on rules.d changes

In reply to Richard Tollerton

Presently, the cache is not regenerated if udev rules are modified, which may cause the cache to preserve an old configuration. To fix, include the size, mtime, and filename of all udev rules in the system configuration.

This change requires stat. If busybox supplies stat, CONFIG_FEATURE_STAT_FORMAT must be enabled.

Signed-off-by Richard Tollerton <[email protected]>
---
 meta/recipes-core/udev/udev/init       | 6 ++++++
 meta/recipes-core/udev/udev/udev-cache | 5 +++++
 2 files changed, 11 insertions(+)
meta/recipes-core/udev/udev/init +6 -0
index 32c677a..94dbba3 100644
@@ -22,9 +22,14 @@ DEVCACHE_REGEN="/dev/shm/udev-regen" # create to request cache regen
 CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices"
 [ -f /proc/atags ] && CMP_FILE_LIST="$CMP_FILE_LIST /proc/atags"
 
+# List of files whose metadata (size/mtime/name) will be included in cached
+# system state.
+META_FILE_LIST="lib/udev/rules.d/* etc/udev/rules.d/*"
+
 # Command to compute system configuration.
 sysconf_cmd () {
 	cat -- $CMP_FILE_LIST
+	stat -L -c '%s %Y %n' -- $META_FILE_LIST | awk -F/ '{print $1 " " $NF;}'
 }
 
 [ -f /etc/default/udev-cache ] && . /etc/default/udev-cache

@@ -76,6 +81,7 @@ case "$1" in
 			    cat <<EOF
 udev: Not using udev cache because of changes detected in the following files:
 udev:     $CMP_FILE_LIST
+udev:     $META_FILE_LIST
 udev: The udev cache will be regenerated. To identify the detected changes,
 udev: compare the cached sysconf at   $SYSCONF_CACHED
 udev: against the current sysconf at  $SYSCONF_TMP
meta/recipes-core/udev/udev/udev-cache +5 -0
index 4d50876..571463f 100644
@@ -25,9 +25,14 @@ DEVCACHE_REGEN="/dev/shm/udev-regen" # create to request cache regen
 CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices"
 [ -f /proc/atags ] && CMP_FILE_LIST="$CMP_FILE_LIST /proc/atags"
 
+# List of files whose metadata (size/mtime/name) will be included in cached
+# system state.
+META_FILE_LIST="lib/udev/rules.d/* etc/udev/rules.d/*"
+
 # Command to compute system configuration.
 sysconf_cmd () {
 	cat -- $CMP_FILE_LIST
+	stat -L -c '%s %Y %n' -- $META_FILE_LIST | awk -F/ '{print $1 " " $NF;}'
 }
 
 [ -f /etc/default/udev-cache ] && . /etc/default/udev-cache
Signature · 1 line
2.1.3
author
#8 lore raw

PATCH v3 8/9 udev-cache: Update cache asynchronously

In reply to Richard Tollerton

Don't hold up the boot while the cache is being updated.

Signed-off-by Richard Tollerton <[email protected]>
Signed-off-by Ben Shelton <[email protected]>
Acked-by Gratian Crisan <[email protected]>
---
 meta/recipes-core/udev/udev/udev-cache | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)
meta/recipes-core/udev/udev/udev-cache +11 -9
index 571463f..3c18061 100644
@@ -44,15 +44,17 @@ fi
 
 if [ "$DEVCACHE" != "" -a -e "$DEVCACHE_REGEN" ]; then
 	echo "Populating dev cache"
-	udevadm control --stop-exec-queue
-        sysconf_cmd > "$SYSCONF_TMP"
-	find /dev -xdev \( -type b -o -type c -o -type l \) | cut -c 2- \
-		| xargs tar cf "${DEVCACHE_TMP}" -T-
-	gzip < "${DEVCACHE_TMP}" > "$DEVCACHE"
-	rm -f "${DEVCACHE_TMP}"
-	mv "$SYSCONF_TMP" "$SYSCONF_CACHED"
-	udevadm control --start-exec-queue
-	rm -f "$DEVCACHE_REGEN"
+	(
+		udevadm control --stop-exec-queue
+		sysconf_cmd > "$SYSCONF_TMP"
+		find /dev -xdev \( -type b -o -type c -o -type l \) | cut -c 2- \
+			| xargs tar cf "${DEVCACHE_TMP}" -T-
+			gzip < "${DEVCACHE_TMP}" > "$DEVCACHE"
+			rm -f "${DEVCACHE_TMP}"
+			mv "$SYSCONF_TMP" "$SYSCONF_CACHED"
+			udevadm control --start-exec-queue
+			rm -f "$DEVCACHE_REGEN"
+	) &
 fi
 
 exit 0
Signature · 1 line
2.1.3
author
#9 lore raw

PATCH v3 9/9 udev-cache: refactor conditionals and error handling

In reply to Richard Tollerton

Most of /etc/init.d/udev-cache is in a conditional block which can be replaced by a [ ... ] || exit 0 to reduce nesting.

This also provides an opportunity to add some additional messages when VERBOSE is set.

Capture and report errors encountered in the cache generation process, using set -e and trap EXIT. These errors were previously being ignored.

Signed-off-by Richard Tollerton <[email protected]>
---
 meta/recipes-core/udev/udev/udev-cache | 35 +++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)
meta/recipes-core/udev/udev/udev-cache +22 -13
index 3c18061..895b197 100644
@@ -42,19 +42,28 @@ if [ "$ROOTFS_READ_ONLY" = "yes" ]; then
     exit 0
 fi
 
-if [ "$DEVCACHE" != "" -a -e "$DEVCACHE_REGEN" ]; then
-	echo "Populating dev cache"
-	(
-		udevadm control --stop-exec-queue
-		sysconf_cmd > "$SYSCONF_TMP"
-		find /dev -xdev \( -type b -o -type c -o -type l \) | cut -c 2- \
-			| xargs tar cf "${DEVCACHE_TMP}" -T-
-			gzip < "${DEVCACHE_TMP}" > "$DEVCACHE"
-			rm -f "${DEVCACHE_TMP}"
-			mv "$SYSCONF_TMP" "$SYSCONF_CACHED"
-			udevadm control --start-exec-queue
-			rm -f "$DEVCACHE_REGEN"
-	) &
+[ "$DEVCACHE" != "" ] || exit 0
+[ "${VERBOSE}" == "no" ] || echo -n "udev-cache: checking for ${DEVCACHE_REGEN}... "
+if ! [ -e "$DEVCACHE_REGEN" ]; then
+	[ "${VERBOSE}" == "no" ] || echo "not found."
+	exit 0
 fi
+[ "${VERBOSE}" == "no" ] || echo "found."
+echo "Populating dev cache"
+
+(
+	set -e
+	trap 'echo "udev-cache: update failed!"' EXIT
+	udevadm control --stop-exec-queue
+	sysconf_cmd > "$SYSCONF_TMP"
+	find /dev -xdev \( -type b -o -type c -o -type l \) | cut -c 2- \
+		| xargs tar cf "${DEVCACHE_TMP}" -T-
+	gzip < "${DEVCACHE_TMP}" > "$DEVCACHE"
+	rm -f "${DEVCACHE_TMP}"
+	mv "$SYSCONF_TMP" "$SYSCONF_CACHED"
+	udevadm control --start-exec-queue
+	rm -f "$DEVCACHE_REGEN"
+	trap - EXIT
+) &
 
 exit 0
Signature · 1 line
2.1.3